The ITIS Logo The Search Results banner for the ITIS Data pages

Taxon author: Britton

ITIS records citing taxon author "Britton"
 
 Kingdom Animalia
  Hyphalinae Britton, 1971 -- valid
  Hyphalus Britton, 1971 -- valid
  Hyphalus insularis Britton, 1971 -- valid
  Hyphalus kuscheli Britton, 1977 -- valid
  Hyphalus prolixus Britton, 1977 -- valid
  Hyphalus ultimus Britton, 1977 -- valid
  Hyphalus wisei Britton, 1973 -- valid
  Lemodinae Lawrence and Britton, 1991 -- valid
  Mecyclothorax ater Britton, 1948 -- valid
  Mecyclothorax exilis Britton, 1948 -- valid
  Mecyclothorax flavomarginatus Britton, 1948 -- valid
  Mecyclothorax incompositus Britton, 1948 -- valid
  Mecyclothorax irregularis Britton, 1948 -- valid
  Mecyclothorax lahainae Britton, 1948 -- valid
  Mecyclothorax minor Britton, 1948 -- valid
  Mecyclothorax paravus Britton, 1948 -- invalid
  Mecyclothorax parvus Britton, 1948 -- valid
  Mecyclothorax proximus Britton, 1948 -- valid
  Mecyclothorax quadratus Britton, 1948 -- valid
  Mecyclothorax sharpi Britton, 1948 -- valid
  Mecyclothorax tantalus Britton, 1948 -- valid
  Mecyclothorax variipes Britton, 1948 -- valid
  Mecyclothorax varipes Britton, 1948 -- invalid
  Myraboliidae Lawrence and Britton, 1991 -- valid
  Tasmosalpingidae Lawrence and Britton, 1991 -- valid
 
 Kingdom Plantae
  Acacia anegadensis Britton -- not accepted -- blackbrush wattle
  Acacia angustissima var. shrevei (Britton & Rose) Isely -- accepted -- Shreve prairie acacia, Shreve's prairie acacia
  Acaciella hirta (Nutt.) Britton & Rose -- not accepted
  Acaciella shrevei Britton & Rose -- not accepted
  Acaciopsis Britton & Rose -- not accepted
  Acaciopsis rigidula (Benth.) Britton & Rose -- not accepted
  Acanthocereus (Engelm. ex A. Berger) Britton & Rose -- accepted -- triangle cactus
  Acanthocereus albicaulis Britton & Rose -- not accepted
  Acanthocereus colombianus Britton & Rose -- not accepted
  Acanthocereus floridanus Small ex Britton & Rose -- not accepted
  Acanthocereus horridus Britton & Rose -- not accepted
  Acanthocereus occidentalis Britton & Rose -- not accepted
  Acanthocereus pentagonus (L.) Britton & Rose -- not accepted
  Acanthocereus subinermis Britton & Rose -- not accepted
  Acanthorhipsalis (K. Schum.) Britton & Rose -- not accepted
  Acer interius Britton -- not accepted
  Acer negundo ssp. interius (Britton) Á. Löve & D. Löve -- not accepted
  Acer negundo var. interius (Britton) Sarg. -- accepted -- ash-leaf maple, boxelder, boxelder maple
  Acer saccharum var. nigrum (F. Michx.) Britton -- not accepted
  Acer stenocarpum Britton -- not accepted
  Acerates viridiflora var. ivesii Britton -- not accepted
  Achimenes gracilis Britton ex Rusby -- not accepted
  Achimenes rusbyi Britton ex Rusby -- not accepted
  Achimenes tubiflora (Hook.) Britton -- not accepted
  Achyranthes peploides (Humb. & Bonpl. ex Schult.) Britton & P. Wilson -- not accepted
  Acisanthera acisanthera (L.) Britton -- not accepted
  Acmispon americanus var. helleri (Britton) Brouillet -- accepted -- Heller's bird's-foot trefoil
  Acmispon helleri (Britton) A. Heller -- not accepted
  Acmispon mearnsii (Britton) Brouillet -- accepted -- Mearns' bird's-foot trefoil
  Acmispon mearnsii var. mearnsii (Britton) Brouillet -- accepted -- Mearns' bird's-foot trefoil
  Adenorachis atropurpurea (Britton) Nieuwl. -- not accepted
  Adenoropium hastatum (Jacq.) Britton & P. Wilson -- not accepted
  Adipera bicapsularis (L.) Britton & Rose ex Britton & P. Wilson -- not accepted
  Adipera corymbosa (Lam.) Britton & Rose -- not accepted
  Adipera laevigata (Willd.) Britton & Rose ex Britton & P. Wilson -- not accepted
  Adipera stahlii (Urb.) Britton & Rose ex Britton & P. Wilson -- not accepted
  Adlumia fungosa (Aiton) Greene ex Britton, Sterns & Poggenb. -- accepted -- Allegheny vine, climbing fumitory, mountain-fringe
  Aeschynomene virginica (L.) Britton, Sterns & Poggenb. -- accepted -- northern jointvetch, sensitive joint-vetch, Virginia jointvetch
  Agalinis aspera (Douglas ex Benth.) Britton -- accepted -- rough foxglove, tall false foxglove
  Agalinis besseyana (Britton) Britton -- not accepted
  Agalinis linifolia (Nutt.) Britton -- accepted -- flaxleaf false foxglove
  Agalinis parvifolia (Chapm.) Small ex Britton -- not accepted
  Agalinis paupercula (A. Gray) Britton -- not accepted -- smallflower false foxglove
  Agalinis paupercula var. paupercula (A. Gray) Britton -- not accepted -- smallflower false foxglove
  Agalinis skinneriana (Alph. Wood) Britton -- accepted -- Skinner's false foxglove
  Agastache anethiodora (Nutt.) Britton -- not accepted
  Agrimonia mollis (Torr. & A. Gray) Britton -- not accepted
  Agrostis hiemalis (Walter) Britton, Sterns & Poggenb. -- not accepted
  Agrostis hyemalis (Walter) Britton, Sterns & Poggenb. -- accepted -- winter bentgrass
  Agrostis hyemalis var. hyemalis (Walter) Britton, Sterns & Poggenb. -- not accepted
  Aklema petiolaris (Sims) Millsp. ex Britton -- not accepted
  Albizia adinocephala (Donn. Sm.) Britton & Rose ex Record -- accepted -- cream albizia
  Albizia carbonaria Britton -- accepted -- naked albizia
  Alliaria alliaria (L.) Britton -- not accepted
  Alloplectus bolivianus (Britton ex Rusby) Wiehler -- not accepted
  Alloplectus grandifolius Britton ex Rusby -- not accepted
  Alnus alnus (L.) Britton -- not accepted
  Alnus noveboracensis Britton -- not accepted
  Aloysia triphylla (L'Hér.) Britton -- not accepted -- lemon beebrush
  Alsinanthe stricta ssp. dawsonensis (Britton) Á. Löve & D. Löve -- not accepted
  Alsine antillana (Urb.) Britton & P. Wilson -- not accepted
  Alsine aquatica (L.) Britton -- not accepted
  Alsine borealis (Bigelow) Britton -- not accepted
  Alsine crassifolia (Ehrh.) Britton -- not accepted
  Alsine fontinalis (Short & Peter) Britton -- not accepted
  Alsine glauca (With.) Britton -- not accepted
  Alsine graminea (L.) Britton -- not accepted
  Alsine holostea (L.) Britton -- not accepted
  Alsine humifusa (Rottb.) Britton -- not accepted
  Alsine longifolia (Muhl. ex Willd.) Britton -- not accepted
  Alsine pubera (Michx.) Britton -- not accepted
  Alsine uliginosa (Murray) Britton -- not accepted
  Amelanchier alabamensis Britton -- not accepted
  Amelanchier arborea var. alabamensis (Britton) G.N. Jones -- not accepted -- Alabama serviceberry
  Amelanchier canadensis var. obovalis (Michx.) Britton, Sterns & Poggenb. -- accepted -- coastal serviceberry
  Amerosedum leibergii (Britton) Á. Löve & D. Löve -- not accepted
  Ammannia koehnei Britton -- not accepted
  Amomis grisea (Kiaersk.) Britton -- not accepted
  Ampelamus albidus (Nutt.) Britton -- not accepted -- honeyvine milkweed
  Amphiglottis anceps (Jacq.) Britton -- not accepted
  Amphiglottis corymbosa auct. non (Lindl.) Britton -- not accepted
  Amphiglottis difformis auct. non (Jacq.) Britton -- not accepted
  Amphiglottis lacera (Lindl.) Britton -- not accepted
  Amphiglottis nocturna (Jacq.) Britton -- not accepted
  Amphiglottis pallidiflora (Hook.) Britton -- not accepted
  Amsonia amsonia (L.) Britton -- not accepted
  Anamomis dicrana (O. Berg) Britton -- not accepted
  Anamomis umbellulifera (Kunth) Britton -- not accepted
  Ancistrocactus (K. Schum.) Britton & Rose -- not accepted
  Ancistrocactus brevihamatus (Engelm.) Britton & Rose -- not accepted
  Ancistrocactus megarrhizus (Rose) Britton & Rose -- not accepted
  Ancistrocactus scheeri (Salm-Dyck) Britton & Rose -- not accepted
  Andrachne cuneifolia Britton -- not accepted
  Andropogon glomeratus (Walter) Britton, Sterns & Poggenb. -- accepted -- bushy bluestem
  Andropogon glomeratus var. glomeratus (Walter) Britton, Sterns & Poggenb. -- accepted -- bushy bluestem
  Anemone decapetala var. heterophylla (Torr. & A. Gray) Britton & Rusby -- not accepted
  Anemone lyallii Britton -- accepted -- Little Mountain thimbleweed
  Anemone multifida var. tetonensis (Porter ex Britton) C.L. Hitchc. -- accepted -- Pacific anemone
  Anemone nemorosa var. lyalli (Britton) Ulbr. -- not accepted
  Anemone nemorosa var. lyallii (Britton) Ulbr. -- not accepted
  Anemone piperi Britton ex Rydb. -- accepted -- Piper's anemone
  Anemone quinquefolia var. lyallii (Britton) B.L. Rob. -- not accepted
  Anemone quinquifolia var. lyallii (Britton) B.L. Rob. -- not accepted
  Anemone tetonensis Porter ex Britton -- not accepted -- Teton anemone
  Angelica villosa (Walter) Britton, Sterns & Poggenb. -- not accepted
  Anguria cookiana Britton -- not accepted
  Anneslea haematostoma (Bertero ex DC.) Britton -- not accepted
  Anneslea portoricensis (Jacq.) Britton -- not accepted
  Anneslea purpurea (L.) Britton -- not accepted
  Anneslia haematomma (Bertero ex DC.) Britton -- not accepted
  Anneslia portoricensis (Jacq.) Britton -- not accepted
  Anneslia purpurea (L.) Britton -- not accepted
  Anogra albicaulis (Pursh) Britton -- not accepted
  Anogra coronopifolia (Torr. & A. Gray) Britton -- not accepted
  Antigonon macrocarpum Britton & Small -- not accepted
  Antirhea portoricensis (Britton & P. Wilson) Standl. -- not accepted -- Puerto Rico quina, quina
  Anychia canadensis (L.) Britton, Sterns & Poggenb. -- not accepted
  Apargia nudicaulis (L.) Britton -- not accepted
  Apocynum milleri Britton -- not accepted
  Aporocactus conzattii Britton & Rose -- not accepted
  Aporocactus leptophis (DC.) Britton & Rose -- not accepted
  Aporocactus martianus Britton & Rose -- not accepted
  Arabidopsis novae-angliae (Rydb.) Britton -- not accepted
  Arabis brachycarpa (Torr. & A. Gray) Britton -- not accepted
  Ardisia luquillensis (Britton) Alain -- accepted -- mountain marlberry
  Arenaria dawsonensis Britton -- not accepted
  Arenaria stricta ssp. dawsonensis (Britton) Maguire -- not accepted
  Arenaria stricta var. dawsonensis (Britton) Scoggan -- not accepted
  Arenaria texana (B.L. Rob.) Britton -- not accepted
  Arequipa Britton & Rose -- not accepted
  Arisaema atrorubens var. stewardsonii (Britton) G.T. Stevens -- not accepted
  Arisaema stewardsonii Britton -- not accepted
  Arisaema triphyllum ssp. stewardsonii (Britton) Huttl. -- not accepted -- Jack in the pulpit
  Arisaema triphyllum var. stewardsonii (Britton) G. T. Stevens ex Wieg. & Eames -- not accepted
  Armatocereus cartwrightianus (Britton & Rose) Backeb. -- accepted
  Armatocereus godingianus (Britton & Rose) Backeb. -- accepted
  Armatocereus godingianus ssp. godingianus (Britton & Rose) Backeb. -- accepted
  Armatocereus humilis (Britton & Rose) Backeb. -- not accepted
  Armatocereus laetus (Britton & Rose) Backeb. -- accepted
  Armoracia armoracia (L.) Britton -- not accepted
  Arnica acaulis (Walter) Britton, Sterns & Poggenb. -- accepted -- common leopardbane
  Aronia arbutifolia var. atropurpurea (Britton) Seymour -- not accepted
  Aronia atropurpurea Britton -- not accepted
  Arrojadoa Britton & Rose -- accepted
  Arrojadoa penicillata (Gürke) Britton & Rose -- accepted
  Arrojadoa rhodantha (Gürke) Britton & Rose -- accepted
  Artemisia kansana Britton -- not accepted
  Asclepias rolfsii Britton ex Vail -- not accepted
  Asclepias tuberosa ssp. rolfsii (Britton ex Vail) Woodson -- accepted -- Rolfs' milkweed
  Asplenium platyneuron (L.) Britton, Sterns & Poggenb. -- accepted -- doradille ébčne, ebony spleenwort
  Asplenium platyneuron var. platyneuron (L.) Britton, Sterns & Poggenb. -- not accepted -- ebony spleenwort
  Aster bracei Britton ex Small -- not accepted -- Brace's aster
  Aster cordifolius var. incisus Britton -- not accepted
  Aster kentuckiensis Britton -- not accepted
  Aster lateriflorus (L.) Britton -- not accepted -- calico aster
  Aster lowrieanus var. incisus (Britton) Porter -- not accepted
  Aster missouriensis Britton non Kuntze -- not accepted
  Aster nebraskensis Britton -- not accepted
  Aster pilosus var. priceae (Britton) Cronquist -- not accepted -- white oldfield aster
  Aster praealtus var. nebraskensis (Britton) Wiegand -- not accepted -- Nebraska aster
  Aster priceae Britton -- not accepted
  Aster pringlei (A. Gray) Britton -- not accepted
  Asterandra grandifolia (L.) Britton -- not accepted
  Astilbe biternata (Vent.) Britton ex Kearney -- accepted -- Appalachian false goat's beard
  Astilbe crenatiloba (Britton) Small -- not accepted -- Roan Mountain false goat's beard
  Astragalus jesupii (Eggl. & E. Sheld.) Britton -- not accepted
  Astrophytum capricorne (A. Dietr.) Britton & Rose -- accepted
  Astrophytum ornatum (DC.) Britton & Rose -- accepted
  Atamosco tubispatha Britton & P. Wilson, non (L'Hér.) M. Gómez -- not accepted
  Audibertia mearnsii Britton -- not accepted
  Austrocactus Britton & Rose -- accepted
  Austrocactus bertinii (Cels ex Hérincq) Britton & Rose -- accepted
  Austrocylindropuntia shaferi (Britton & Rose) Backeb. -- accepted
  Baccharis neglecta Britton -- accepted -- Roosevelt-weed, Rooseveltweed
  Badiera portoricensis Britton -- not accepted
  Bahia dissecta (A. Gray) Britton -- not accepted -- ragleaf bahia
  Bartonia virginica (L.) Britton, Sterns & Poggenb. -- accepted -- bartonie de Virginie, yellow screwstem
  Batocydia unguis (L.) Mart. ex Britton -- not accepted
  Batocydia unguis-cati (L.) Mart. ex Britton -- not accepted
  Batrachium porteri (Britton) Britton -- not accepted
  Bauhinia congesta (Britton & Rose) Lundell -- not accepted
  Bauhinia jermyana (Britton) Lundell -- not accepted
  Bergerocactus Britton & Rose -- accepted -- snakecactus
  Bergerocactus emoryi (Engelm.) Britton & Rose -- accepted -- golden snakecactus, Órgano aterciopelado
  Bergerocereus emoryi (Engelm.) Britton & Rose -- not accepted
  Besleria longipedunculata Britton ex Rusby -- accepted
  Besleria montana Britton ex Rusby -- accepted
  Besleria sprucei Britton ex Rusby -- accepted
  Betula alleghaniensis Britton -- accepted -- yellow birch
  Betula alleghaniensis var. alleghaniensis Britton -- not accepted -- yellow birch
  Betula ersinifera Britton -- not accepted
  Betula piperi Britton -- not accepted
  Betula resinifera Britton -- not accepted
  Betula X sandbergii Britton -- accepted -- Sandberg's birch
  Betula X utahensis Britton (pro sp.) -- accepted -- northwestern paper birch
  Bidens acuta (Wiegand) Britton -- not accepted
  Bidens aristosa (Michx.) Britton -- accepted -- bearded beggarticks, long-bracted beggar-ticks, tickseed sunflower
  Bidens bidentoides (Nutt.) Britton -- accepted -- Delmarva beggarticks
  Bidens coronata (L.) Britton -- not accepted -- crowned beggarticks
  Bidens discoidea (Torr. & A. Gray) Britton -- accepted -- discoid beggarticks, small beggarticks, swamp beggar-ticks
  Bidens involucrata (Nutt.) Britton -- not accepted
  Bidens laevis (L.) Britton, Sterns & Poggenb. -- accepted -- bur marigold, smooth beggarticks
  Bidens trichosperma (Michx.) Britton -- accepted -- crowned beggarticks
  Boebera papposa (Vent.) Rydb. ex Britton -- not accepted
  Bolboschoenus novae-angliae (Britton) S.G. Sm. -- accepted -- New England bulrush
  Borrichia X cubana Britton & S.F. Blake (pro sp.) -- accepted -- Cuban borrichia
  Borzicactus acanthurus (Vaupel) Britton & Rose -- not accepted
  Borzicactus aurivillus (K. Schum.) Britton & Rose -- not accepted
  Borzicactus decumbens (Vaupel) Britton & Rose -- not accepted
  Borzicactus fieldianus Britton & Rose -- not accepted
  Borzicactus icosagonus (Kunth) Britton & Rose -- not accepted
  Borzicactus morleyanus Britton & Rose -- not accepted
  Borzicactus plagiostoma (Vaupel) Britton & Rose -- not accepted
  Borzicactus sepium (Kunth) Britton & Rose -- not accepted
  Bouchetia anomala (Miers) Britton & Rusby -- accepted
  Brachyactis angusta (Lindl.) Britton -- not accepted
  Brachycereus Britton & Rose -- accepted
  Brachychaeta sphacelata (Raf.) Britton -- not accepted
  Bradburya floridana Britton -- not accepted
  Bramia rotundifolia (Michx.) Britton -- not accepted
  Brasiliopuntia bahiensis (Britton & Rose) A. Berger -- not accepted
  Brauneria pallida (Nutt.) Britton -- not accepted
  Brauneria purpurea (L.) Britton -- not accepted
  Browningia Britton & Rose -- accepted
  Browningia candelaris (Meyen) Britton & Rose -- accepted
  Browningia candelaris ssp. candelaris (Meyen) Britton & Rose -- accepted
  Bruchia drummnondii Hampe Ex Britton -- accepted
  Brysonima horneana Britton & Small -- not accepted
  Brysonima X ophiticola Small ex Britton -- not accepted
  Bulbostylis antillana (Britton) Fernald -- not accepted
  Bulbostylis capillaris ssp. antillana (Britton) T. Koyama -- not accepted -- densetuft hairsedge
  Bulbostylis curassavica (Britton) Kük. ex Ekman -- accepted -- West Indian hairsedge
  Bursa bursa-pastoris (L.) Britton -- not accepted
  Byrsonima horneana Britton & Small -- not accepted
  Byrsonima X ophiticola Small ex Britton -- accepted
  Cabomba piauhyensis sensu Britton & P. Wilson and sensu Alain, non Gardner -- not accepted
  Caconapea stricta (Schrad.) Britton -- not accepted
  Cactus broadwayi Britton & Rose -- not accepted
  Caesalpinia clementis (Britton) Leon -- not accepted
  Caesalpinia culebrae (Britton & P. Wilson) Alain -- not accepted -- amarillo mato, smooth yellow nicker
  Caesalpinia monensis Britton -- accepted -- black nicker, negro mato
  Caesalpinia myabensis Britton -- not accepted
  Caesalpinia peninsularis (Britton) Eifert -- not accepted -- peninsular holdback
  Caesalpinia portoricensis (Britton & P. Wilson) Alain -- not accepted -- brown mato, brown nicker
  Caesalpinia pumila (Britton & Rose) F.J. Herm. -- accepted
  Caesalpinia wootonii (Britton) Eifert ex Isely -- not accepted -- Wooton's holdback
  Calophyllum antillanum Britton -- not accepted -- Alexandrian laurel, Antilles calophyllum, mast wood, Santa Maria
  Calophyllum brasiliense var. antillanum (Britton) Standl. -- not accepted
  Calopogon tuberosus (L.) Britton, Sterns & Poggenb. -- accepted -- tuberous grasspink
  Calopogon tuberosus var. tuberosus (L.) Britton, Sterns & Poggenb. -- accepted -- tuberous grasspink
  Calyptracordia alba auct. non (Jacq.) Britton -- not accepted
  Calyptracordia alba (Jacq.) Britton -- not accepted
  Calyptranthes portoricensis Britton -- not accepted -- Puerto Rico lidflower
  Cananga blainii (Griseb.) Britton -- not accepted
  Cananga caribaea (Urb.) Britton -- not accepted
  Capnoides campestre Britton -- not accepted
  Capnoides micranthum (Engelm. ex A. Gray) Britton -- not accepted
  Capnoides montanum (Engelm.) Britton -- not accepted
  Carara didyma (L.) Britton -- not accepted
  Cardamine arenicola Britton -- not accepted
  Cardamine bulbosa (Schreb. ex Muhl.) Britton, Sterns & Poggenb. -- accepted -- bulb bittercress, bulbous bitter-cress, bulbous bittercress, cardamine bulbeuse
  Cardamine douglassii Britton -- accepted -- limestone bittercress
  Cardamine parviflora var. arenicola (Britton) O.E. Schulz -- not accepted -- sand bittercress
  Carduus smallii (Britton) H.E. Ahles -- not accepted
  Carex atratiformis Britton -- accepted -- black sedge, scrabrous black sedge
  Carex baileyi Britton -- accepted -- Bailey's sedge
  Carex bicknellii Britton -- accepted -- Bicknell's sedge, carex de Bicknell
  Carex bicknellii var. bicknellii Britton -- not accepted -- Bicknell's sedge
  Carex bonanzensis Britton -- accepted -- Yukon sedge
  Carex capillaris var. williamsii (Britton) B. Boivin -- not accepted
  Carex cristatella Britton -- accepted -- crested sedge
  Carex magellanica var. irrigua (Wahlenb.) Britton, Sterns & Poggenb. -- not accepted
  Carex mainensis Porter ex Britton -- not accepted
  Carex shriveri Britton -- not accepted
  Carex suberecta (Olney) Britton -- accepted -- prairie straw sedge
  Carex tribuloides var. moniliformis (Tuck.) Britton -- not accepted
  Carex williamsii Britton -- accepted -- Williams' sedge
  Carex X mainensis Porter ex Britton (pro sp.) -- not accepted -- Maine sedge
  Carnegia Britton & Rose -- not accepted
  Carnegia gigantea (Engelm.) Britton & Rose -- not accepted
  Carnegiea Britton & Rose -- accepted -- saguaro
  Carnegiea gigantea (Engelm.) Britton & Rose -- accepted -- Saguaro, saguaro
  Carya microcarpa (Nutt.) Britton -- not accepted
  Casparea congesta Britton & Rose -- not accepted
  Casparea jermyana Britton -- not accepted
  Caspareopsis monandra (Kurz) Britton & Rose -- not accepted
  Casparia congesta Britton & Rose -- not accepted
  Casparia jermyana Britton -- not accepted
  Cassia antillana (Britton & Rose) Alain -- not accepted
  Cassia fasciculata var. ferrisiae (Britton ex Britton & Rose) B.L. Turner -- not accepted
  Cassia orcuttii (Britton & Rose) B.L. Turner -- not accepted
  Castalia amazonum (Mart. & Zucc.) Britton & P. Wilson -- not accepted
  Castalia jamesoniana (Planch.) Britton & P. Wilson -- not accepted
  Castalia pulchella (DC.) Britton -- not accepted
  Castalia rudgeana (G. Mey.) Britton & P. Wilson -- not accepted
  Castilleja integra var. gloriosa (Britton) Cockerell -- accepted -- squawfeather, wholeleaf Indian paintbrush
  Celeri graveolens (L.) Britton -- not accepted
  Centaurea X moncktonii C.E. Britton -- accepted -- meadow knapweed, protean knapweed
  Centrosema floridanum (Britton) Lakela -- not accepted
  Cephalocereus alensis (F.A.C. Weber ex Rol.-Goss.) Britton & Rose -- not accepted
  Cephalocereus arrabidae (Lem.) Britton & Rose -- not accepted
  Cephalocereus bahamensis Britton -- not accepted
  Cephalocereus barbadensis Britton & Rose -- not accepted
  Cephalocereus brasiliensis Britton & Rose -- not accepted
  Cephalocereus brooksianus Britton & Rose -- not accepted
  Cephalocereus catingicola (Gürke) Britton & Rose -- not accepted
  Cephalocereus chrysacanthus (F.A.C. Weber) Britton & Rose -- not accepted
  Cephalocereus collinsii Britton & Rose -- not accepted
  Cephalocereus dybowskii (Rol.-Goss.) Britton & Rose -- not accepted
  Cephalocereus fluminensis (Miq.) Britton & Rose -- not accepted
  Cephalocereus gaumeri Britton & Rose -- not accepted
  Cephalocereus gounellei (F.A.C. Weber ex K. Schum.) Britton & Rose -- not accepted
  Cephalocereus keyensis Britton & Rose -- not accepted
  Cephalocereus lanuginosus (L.) Britton & Rose -- not accepted
  Cephalocereus leucocephalus (Poselg.) Britton & Rose -- not accepted
  Cephalocereus leucostele (Gürke) Britton & Rose -- not accepted
  Cephalocereus millspaughii Britton -- not accepted
  Cephalocereus monoclonos (DC.) Britton & Rose -- not accepted
  Cephalocereus moritzianus (Otto) Britton & Rose -- not accepted
  Cephalocereus nobilis (Haw.) Britton & Rose -- not accepted
  Cephalocereus pentaedrophorus (Labour.) Britton & Rose -- not accepted
  Cephalocereus phaeacanthus (Gürke) Britton & Rose -- not accepted
  Cephalocereus piauhyensis (Gürke) Britton & Rose -- not accepted
  Cephalocereus polygonus (Lam.) Britton & Rose -- not accepted
  Cephalocereus polylophus (DC.) Britton & Rose -- not accepted
  Cephalocereus purpusii Britton & Rose -- not accepted
  Cephalocereus robinii (Lem.) Britton & Rose -- not accepted
  Cephalocereus robustus Britton & Rose -- not accepted
  Cephalocereus royenii (L.) Britton & Rose -- not accepted
  Cephalocereus scoparius (Polseg.) Britton & Rose -- not accepted
  Cephalocereus smithianus Britton & Rose -- not accepted
  Cephalocereus swartzii (Griseb.) Britton & Rose -- not accepted
  Cephalocereus tweedyanus Britton & Rose -- not accepted
  Cephalocereus zehnteri Britton & Rose -- not accepted
  Cerastium arvense ssp. maximum (Hollick & Britton) Ugbor. -- not accepted -- field chickweed
  Cerastium arvense ssp. velutinum var. velutinum (Raf.) Britton -- not accepted -- field chickweed
  Cerastium arvense ssp. velutinum var. villosum (Muhl. ex Darl.) Hollick & Britton -- not accepted -- field chickweed
  Cerastium arvense var. maximum Hollick & Britton -- not accepted
  Cerastium arvense var. oblongifolium (Torr.) Hollick & Britton -- not accepted
  Cerastium arvense var. velutinum (Raf.) Britton -- not accepted -- field chickweed
  Cerastium arvense var. villosum (Muhl. ex Darl.) Hollick & Britton -- not accepted -- field chickweed
  Cerastium cerastioides (L.) Britton -- not accepted -- mountain chickweed, starwort chickweed
  Cerastium cerastoides (L.) Britton -- accepted -- mountain chickweed
  Cerastium longepedunculatum Muhl. ex Britton -- not accepted
  Cerastium texanum Britton -- accepted -- Texas chickweed, Texas mouse-ear chickweed
  Cereus albicaulis (Britton & Rose) Leutzelb. -- accepted
  Cereus argentinensis Britton & Rose -- accepted
  Cereus diffusus (Britton & Rose) Werderm. -- not accepted
  Cereus eriophorus var. fragrans (Small ex Britton & Rose) L.D. Benson -- not accepted -- fragrant prickly-apple
  Cereus gracilis var. simpsonii (Small ex Britton & Rose) L.D. Benson -- not accepted -- Simpson's prickly-apple
  Cereus grantianus (Britton) H.P. Kelsey & Dayton -- not accepted
  Cereus grenadensis Britton & Rose -- not accepted
  Cereus portoricensis (Britton) Urb. -- not accepted
  Cereus robinii var. keyensis (Britton & Rose) L.D. Benson -- not accepted
  Cereus smithianus (Britton & Rose) Werderm. -- not accepted
  Chamaecereus Britton & Rose -- not accepted
  Chamaecereus silvestrii (Speg.) Britton & Rose -- not accepted
  Chamaecrista chamaecristoides var. cruziana (Britton & Rose) H.S. Irwin & Barneby -- accepted -- beach sensitive pea
  Chamaecrista cruziana Britton & Rose -- not accepted
  Chamaecrista exunguis (Urb.) Britton -- not accepted
  Chamaecrista granulata (Urb.) Britton -- not accepted
  Chamaecrista mohrii (Pollard) Small ex Britton & Rose -- not accepted
  Chamaecrista swartzii (Wikstr.) Britton -- not accepted
  Chamaecyparis thyoides (L.) Britton, Sterns & Poggenb. -- accepted -- Atlantic white cedar, Atlantic white-cedar, southern white cedar, southern white-cedar
  Chamaefistula antillana Britton & Rose -- not accepted
  Chamaeraphis caudata (Lam.) Britton -- not accepted
  Chamaeraphis caudata var. caudata (Lam.) Britton -- not accepted
  Chamaesaracha coniodes (Moric. ex Dunal) Britton -- accepted -- gray false nightshade, gray five eyes
  Chamaesyce articulata (Burm.) Britton -- not accepted -- jointed sandmat
  Chamaesyce cowellii Millsp. ex Britton -- not accepted -- Cowell's sandmat
  Chamaesyce jenningsii Millsp. ex Britton -- not accepted
  Cheirinia aspera (Nutt.) Britton -- not accepted
  Chiapasia Britton & Rose -- not accepted
  Chiapasia nelsonii (Britton & Rose) Britton & Rose -- not accepted
  Chiococca pinetorum Britton ex Millsp. -- not accepted
  Chloris morales-coelloi León ex Britton -- not accepted
  Chondrophora nudata (Michx.) Britton -- not accepted
  Chromolaena borinquensis (Britton) R.M. King & H. Rob. -- accepted -- limestone thoroughwort
  Chrysobalanus savannarum Britton -- not accepted
  Chrysopsis nuttallii Britton -- not accepted
  Chrysopsis pilosa (Walter) Britton non Nutt. -- not accepted -- soft goldenaster
  Chrysothamnus nauseosus (Pall. ex Pursh) Britton -- not accepted -- gray rabbitbrush
  Chrysothamnus nauseosus ssp. nauseosus (Pall. ex Pursh) Britton -- not accepted -- rubber rabbitbrush
  Chrysothamnus nauseosus var. nauseosus (Pall. ex Pursh) Britton -- not accepted
  Ciclospermum leptophyllum (Pers.) Sprague ex Britton & P. Wilson -- not accepted -- marsh parsley
  Cirsium muticum var. subpinnatifidum (Britton) Fernald -- not accepted
  Cirsium nebraskense (Britton) Lunell -- not accepted
  Cirsium smallii Britton -- not accepted
  Cleistocactus anguinus (Gürke) Britton & Rose -- not accepted
  Cleistocactus fieldianus (Britton & Rose) D.R. Hunt -- accepted
  Cleistocactus fieldianus ssp. fieldianus (Britton & Rose) D.R. Hunt -- accepted
  Cleistocactus smaragdiflorus (F.A.C. Weber) Britton & Rose -- accepted
  Clematis addisonii Britton -- accepted -- Addison's leather flower, Addison's virgin's bower
  Clematis viornioides Britton -- not accepted
  Cliftonia monophylla (Lam.) Britton ex Sarg. -- accepted -- black titi, buckwheat tree
  Clistanthocereus fieldianus (Britton & Rose) Backeb. -- not accepted
  Coccoloba borinquensis Britton -- not accepted
  Cochemiea halei (Brandegee) Britton & Rose -- not accepted
  Cochemiea poselgeri (Hildm.) Britton & Rose -- not accepted
  Cockerellia cockerellii (Britton) Á. Löve & D. Löve -- not accepted
  Codonanthe triplinervia Britton -- not accepted
  Cojoba Britton & Rose -- accepted
  Cojoba arborea (L.) Britton & Rose -- accepted -- wild tamarind
  Cojoba graciliflora (S.F. Blake) Britton & Rose -- accepted -- Guadeloupe blackbead
  Columnea aripoensis Britton -- not accepted
  Columnea boliviana Britton ex Rusby -- not accepted
  Columnea cubensis (Urb.) Britton -- not accepted
  Columnea harrisii (Urb.) Britton ex C.V. Morton -- accepted
  Columnea scandens var. aripoensis (Britton) C.V. Morton -- not accepted
  Columnea tocoensis Britton -- not accepted
  Comocladia cuneata Britton -- accepted -- wedgeleaf maidenplum
  Conami portoricensis (Kuntze) Britton -- not accepted
  Conioselinum chinense (L.) Britton, Sterns & Poggenb. -- accepted -- Chinese hemlockparsley
  Copernicia alba Morong ex Morong & Britton -- accepted -- copernicia
  Copiapoa Britton & Rose -- accepted
  Copiapoa cinerascens (Salm-Dyck) Britton & Rose -- accepted
  Copiapoa cinerea (Phil.) Britton & Rose -- accepted
  Copiapoa cinerea ssp. cinerea (Phil.) Britton & Rose -- accepted
  Copiapoa coquimbana (Karw. ex Rümpler) Britton & Rose -- accepted
  Copiapoa echinoides (Lem.) Britton & Rose -- accepted
  Copiapoa marginata (Salm-Dyck) Britton & Rose -- accepted
  Copiapoa megarhiza Britton & Rose -- accepted
  Copiapoa megarhiza var. megarhiza Britton & Rose -- accepted
  Cordyline guineensis (L.) Britton -- not accepted
  Coreopsis major var. oemleri (Elliot) Britton ex Small & Vail -- not accepted
  Coriflora addisonii (Britton) W.A. Weber -- not accepted
  Corryocactus Britton & Rose -- accepted
  Corryocactus brachypetalus (Vaupel) Britton & Rose -- accepted
  Corryocactus brevistylus (K. Schum. ex Vaupel) Britton & Rose -- accepted
  Corryocactus brevistylus ssp. brevistylus (K. Schum. ex Vaupel) Britton & Rose -- not accepted
  Corryocactus melanotrichus (K. Schum.) Britton & Rose -- accepted
  Corydalis campestris (Britton) J. Buchholz & E.J. Palmer -- not accepted
  Coryphantha aggregata (Engelm.) Britton & Rose -- not accepted
  Coryphantha arizonica (Engelm. ex Brew & Wats) Britton & Rose -- not accepted
  Coryphantha bumamma (Ehrenb.) Britton & Rose -- not accepted
  Coryphantha chaffeyi (Britton & Rose) Fosberg -- not accepted -- Chaffey's cory cactus
  Coryphantha chlorantha (Engelm.) Britton & Rose -- not accepted
  Coryphantha compacta (Engelm.) Britton & Rose -- accepted
  Coryphantha connivens Britton & Rose -- not accepted
  Coryphantha cubensis Britton & Rose -- not accepted
  Coryphantha deserti (Engelm.) Britton & Rose -- not accepted
  Coryphantha durangensis (Runge ex K. Schum.) Britton & Rose -- accepted
  Coryphantha durangensis ssp. durangensis (Runge ex K. Schum.) Britton & Rose -- accepted
  Coryphantha echinoidea (Quehl) Britton & Rose -- accepted
  Coryphantha echinus (Engelm.) Britton & Rose -- not accepted -- Biznaga-partida erizo, rhinoceros cactus
  Coryphantha guerkeana (Boed.) Britton & Rose -- not accepted
  Coryphantha macromeris ssp. runyonii (Britton & Rose) N.P. Taylor -- accepted
  Coryphantha macromeris var. runyonii (Britton & Rose) L.D. Benson -- not accepted -- Runyon's beehive cactus
  Coryphantha missouriensis (Sweet) Britton & Rose -- not accepted
  Coryphantha muehlenpfordtii (Poselg.) Britton & Rose -- not accepted
  Coryphantha neomexicana (Engelm.) Britton & Rose -- not accepted
  Coryphantha nickelsiae (K. Brandegee) Britton & Rose -- accepted -- Biznaga-partida de Laredo, Nickels' cactus
  Coryphantha octacantha (DC.) Britton & Rose -- accepted
  Coryphantha pallida Britton & Rose -- accepted
  Coryphantha pallida ssp. pallida Britton & Rose -- accepted
  Coryphantha palmeri Britton & Rose -- not accepted
  Coryphantha pectinata (Engelm.) Britton & Rose -- not accepted
  Coryphantha poselgeriana (A. Dietr.) Britton & Rose -- accepted
  Coryphantha radians (DC.) Britton & Rose -- not accepted
  Coryphantha recurvata (Engelm.) Britton & Rose -- accepted -- Biznaga-partida de espinas curvas, Santa Cruz beehive cactus
  Coryphantha retusa (Pfeiff.) Britton & Rose -- accepted
  Coryphantha robustispina (A. Schott ex Engelm.) Britton & Rose -- accepted -- Biznaga-partida de espinas gruesas
  Coryphantha robustispina ssp. robustispina (A. Schott ex Engelm.) Britton & Rose -- accepted
  Coryphantha runyonii Britton & Rose -- not accepted
  Coryphantha salm-dyckiana (Scheer) Britton & Rose -- not accepted
  Coryphantha similis (Engelm.) Britton & Rose -- not accepted
  Coryphantha sneedii (Britton & Rose) A. Berger -- not accepted
  Coryphantha sneedii (Britton & Rose) A. Berger -- not accepted -- Sneed pincushion cactus
  Coryphantha sneedii var. sneedii (Britton & Rose) A. Berger -- not accepted -- Sneed pincushion cactus
  Coryphantha sulcata (Engelm.) Britton & Rose -- accepted -- finger cactus, pineapple cactus
  Coryphantha sulcata var. sulcata (Engelm.) Britton & Rose -- not accepted -- pineapple cactus
  Coryphantha vivipara (Nutt.) Britton & Rose -- not accepted
  Corytoplectus grandifolius (Britton ex Rusby) Rodr.-Flores & L.E. Skog -- accepted
  Cracca cathartica (Sessé & Moc.) Britton & Millsp. -- not accepted
  Crantzia ambigua (Urb.) Britton -- not accepted
  Crataegus chrysocarpa var. piperi (Britton) Kruschke -- accepted -- Piper's hawthorn
  Crataegus columbiana var. occidentalis (Britton) Dorn -- not accepted
  Crataegus columbiana var. piperi (Britton) Eggl. -- not accepted
  Crataegus macracantha var. occidentalis (Britton) Eggl. -- not accepted
  Crataegus margarettae var. brownii (Britton) Sarg. -- accepted
  Crataegus margarettiae var. brownii (Britton) Sarg. -- not accepted
  Crataegus nitida (Engelm. ex Britton & A. Br.) Sarg. -- accepted -- glossy hawthorn
  Crataegus occidentalis Britton -- not accepted
  Crataegus piperi Britton -- not accepted -- Piper's hawthorn
  Crataegus porteri Britton -- not accepted
  Crataegus pruinosa var. porteri (Britton) Eggl. -- not accepted
  Crataegus punctata var. canescens Britton -- not accepted
  Crataegus succulenta var. occidentalis Britton -- not accepted
  Crataegus vailiae Britton -- accepted -- Miss Vail's hawthorn
  Crataegus viridis var. nitida Engelm. ex Britton & A. Br. -- not accepted
  Crescentia portoricensis Britton -- accepted -- calabash tree, higuero de sierra
  Critonia portoricensis (Urb.) Britton & P. Wilson -- accepted -- Puerto Rico thoroughwort
  Crocanthemum canadense (L.) Britton -- not accepted
  Crocanthemum corymbosum (Michx.) Britton -- not accepted
  Crocanthemum majus Britton -- not accepted
  Crocanthemum nashii (Britton) Barnhart -- not accepted
  Croton cueroensis Britton & P. Wilson -- not accepted
  Croton fishlockii Britton -- accepted -- Fishlock's croton
  Croton rigidus Britton -- not accepted -- yellow balsam
  Croton rusbyi Britton ex Rusby -- accepted
  Cumulopuntia ignota (Britton & Rose) F. Ritter -- not accepted
  Cunila origanoides (L.) Britton -- accepted -- common dittany
  Curcas curcas (L.) Britton & Millsp. -- not accepted
  Curcas hernandiifolia (Vent.) Britton -- not accepted
  Cyclospermum leptophyllum (Pers.) Sprague ex Britton & P. Wilson -- accepted -- marsh parsley
  Cylindropuntia alamosensis (Britton & Rose) Backeb. -- not accepted
  Cylindropuntia alcahes var. burrageana (Britton & Rose) Rebman -- accepted
  Cylindropuntia burrageana (Britton & Rose) Backeb. -- not accepted
  Cylindropuntia caribaea (Britton & Rose) F.M. Knuth -- accepted
  Cylindropuntia X viridiflora (Britton & Rose) F.M. Knuth -- accepted
  Cymanchum anedadense (Britton) Alain -- not accepted
  Cymanchum monense (Britton) Alain -- not accepted
  Cynanchum anegadense (Britton) Alain -- not accepted -- Caribbean swallow-wort
  Cynanchum monense (Britton) Alain -- not accepted -- Mona Island swallow-wort
  Cynoctonum mitreola (L.) Britton -- not accepted
  Cyperus blodgettii Britton -- not accepted -- Blodgett's flatsedge
  Cyperus buckleyi Britton -- not accepted
  Cyperus bushii Britton -- not accepted
  Cyperus calcicola Britton -- not accepted -- Caribbean flatsedge
  Cyperus careyi Britton -- not accepted
  Cyperus cayennensis (Lam.) Britton, non Willd. ex Link -- not accepted
  Cyperus cylindricus (Elliott) Britton -- not accepted
  Cyperus deeringianus Britton & Small -- not accepted
  Cyperus diandrus var. capitatus Britton -- not accepted
  Cyperus esculentus var. angustispicatus Britton -- not accepted
  Cyperus esculentus var. hermannii (Buckley) Britton -- accepted -- chufa flatsedge, yellow nutgrass, yellow nutsedge
  Cyperus fendlerianus var. debilis (Britton) Kük. -- not accepted
  Cyperus floridanus Britton -- not accepted -- Florida flatsedge
  Cyperus granularis (Desf.) Britton -- not accepted
  Cyperus halei Torr. ex Britton -- not accepted
  Cyperus hallii Britton -- not accepted
  Cyperus hansenii Britton -- not accepted
  Cyperus litoreus (C.B. Clarke) Britton -- not accepted
  Cyperus martindalei auct. non Britton -- not accepted
  Cyperus multiflorus (Britton) Small -- not accepted
  Cyperus nashii Britton -- not accepted
  Cyperus niger var. capitatus (Britton) O'Neill -- not accepted
  Cyperus odoratus var. squarrosus (Britton) S.D. Jones, Wipff & R. Carter -- not accepted
  Cyperus parishii Britton -- accepted -- Parish flatsedge, Parish's flatsedge, Parish's nutgrass
  Cyperus pollardii Britton -- not accepted
  Cyperus pringlei Britton -- not accepted
  Cyperus regiomontanus Britton -- accepted -- Monterey flatsedge
  Cyperus retrorsus var. deeringianus (Britton & Small) Fernald & Griscom -- not accepted
  Cyperus retrorsus var. nashii (Britton) Fernald & Griscom -- not accepted
  Cyperus rusbyi Britton -- not accepted
  Cyperus speciosus var. squarrosus Britton -- not accepted
  Cyperus torreyi Britton -- not accepted
  Cyperus winkleri Britton & Small -- not accepted
  Cyperus wrightii Britton -- not accepted
  Cyrtospadix bicolor (Aiton) Britton & P. Wilson -- not accepted
  Danthonia domingensis ssp. shrevei (Britton) Conert -- accepted
  Danthonia shrevei Britton -- not accepted
  Dasistoma virginica (L.) Britton -- not accepted
  Dasystephana grayi (Kusnez.) Britton -- not accepted
  Dasystephana linearis (Froel.) Britton -- not accepted
  Deamia Britton & Rose -- not accepted
  Deamia testudo (Karw. ex Zucc.) Britton & Rose -- not accepted
  Dendrocereus Britton & Rose -- accepted
  Dendrocereus nudiflorus (Engelm. ex Sauvalle) Britton & Rose -- accepted
  Dendrocereus undulosus (DC.) Britton & Rose -- accepted
  Denmoza Britton & Rose -- accepted
  Denmoza rhodacantha (Salm-Dyck) Britton & Rose -- accepted
  Dentaria incisifolia Eames ex Britton -- not accepted
  Descurainia incisa (Engelm. ex A. Gray) Britton -- accepted -- mountain tansymustard
  Descurainia incisa ssp. incisa (Engelm. ex A. Gray) Britton -- accepted -- mountain tansymustard
  Descurainia incisa var. incisa (Engelm. ex A. Gray) Britton -- not accepted
  Descurainia pinnata (Walter) Britton -- accepted -- green tansymustard, pinnate tansy mustard, pinnate tansymustard, tansymustard, western tansymustard
  Descurainia pinnata ssp. pinnata (Walter) Britton -- accepted -- western tansymustard
  Descurainia pinnata ssp. pinnata var. pinnata (Walter) Britton -- not accepted -- western tansymustard
  Desmanthus covillei (Britton & Rose) Wiggins ex B.L. Turner -- accepted -- Coville's bundleflower
  Desmodium tweedyi Britton -- accepted -- Tweedy's ticktrefoil
  Diamorpha cymosa (Nutt.) Britton ex Small -- not accepted
  Diamorpha smallii Britton ex Small -- accepted -- elf orpine
  Diapedium krugii (Urb.) Britton -- not accepted
  Dichromena floridensis Britton -- not accepted
  Dichromena nivea (Boeckeler) Boeckeler ex Britton -- not accepted
  Dichylium Britton -- not accepted
  Dichylium oerstedianum (Klotzsch & Garcke) Britton -- not accepted
  Didymopanax gleasonii Britton & P. Wilson -- not accepted
  Discocactus bahiensis Britton & Rose -- accepted
  Discocactus hartmannii (K. Schum.) Britton & Rose -- accepted
  Discocactus heptacanthus (Barb. Rodr.) Britton & Rose -- accepted
  Discocactus heptacanthus ssp. heptacanthus (Barb. Rodr.) Britton & Rose -- not accepted
  Discocactus zehntneri Britton & Rose -- accepted
  Discocactus zehntneri ssp. zehntneri Britton & Rose -- accepted
  Disocactus eichlamii (Weing.) Britton & Rose -- accepted
  Disocactus nelsonii (Britton & Rose) Linding. -- accepted
  Disocactus nelsonii ssp. nelsonii (Britton & Rose) Linding. -- accepted
  Disporum hookeri var. parvifolium (S. Watson) Britton -- not accepted -- drops of gold
  Disporum maculatum (Buckley) Britton -- not accepted -- yellow mandarin
  Disporum parvifolium (S. Watson) Britton -- not accepted
  Disporum trachyandrum (Torr.) Britton -- not accepted
  Ditremexa hirsuta (L.) Britton & Rose ex Britton & P. Wilson -- not accepted
  Ditremexa marilandica (L.) Britton & Rose -- not accepted
  Ditremexa medsgeri (Shafer) Britton & Rose -- not accepted
  Ditremexa occidentalis (L.) Britton & Rose ex Britton & P. Wilson -- not accepted
  Doellingeria humilis (Willd.) Britton -- not accepted
  Doellingeria umbellata var. pubens (A. Gray) Britton -- accepted -- parasol whitetop
  Dolicholus pyramidalis auct. non (Lam.) Britton & P. Wilson -- not accepted
  Dolichothele (K. Schum.) Britton & Rose -- not accepted
  Dolichothele longimamma (DC.) Britton & Rose -- not accepted
  Dolichothele nelsonii (Britton & Rose) Backeb. -- not accepted
  Dolichothele sphaerica (A. Dietr.) Britton & Rose -- not accepted
  Dolichothele uberiformis (Zucc. ex Pfeiff.) Britton & Rose -- not accepted
  Dondia depressa auct. non (Pursh) Britton -- not accepted
  Dracocephalum nuttallii Britton -- not accepted
  Dryopteris dryopteris (L.) Britton -- not accepted
  Dryopteris X algonquinensis D.M. Britton -- accepted -- Algonquin woodfern
  Duchartrea sintenisii (Urb.) Britton -- not accepted
  Dudleya Britton & Rose -- accepted
  Dudleya caespitosa (Haw.) Britton & Rose -- not accepted -- sealettuce
  Dudleya cespitosa (Haw.) Britton & Rose -- accepted -- sealettuce
  Dudleya cotyledon (Jacq.) Britton & Rose -- not accepted
  Dudleya cymosa (Lem.) Britton & Rose -- accepted -- canyon liveforever
  Dudleya cymosa ssp. cymosa (Lem.) Britton & Rose -- accepted -- canyon liveforever
  Dudleya cymosa ssp. ovatifolia (Britton) Moran -- accepted -- Santa Monica Mountains dudleya
  Dudleya farinosa (Lindley) Britton & Rose -- accepted -- powdery liveforever
  Dudleya lanceolata (Nutt.) Britton & Rose -- accepted -- lanceleaf liveforever
  Dudleya laxa (Lindley) Britton & Rose -- not accepted
  Dudleya nevadensis (S. Watson) Britton & Rose -- not accepted
  Dudleya palmeri (S. Watson) Britton & Rose -- accepted -- Palmer's liveforever
  Dudleya pulverulenta (Nutt.) Britton & Rose -- accepted -- chalk dudleya, chalk liveforever
  Dudleya pulverulenta ssp. pulverulenta (Nutt.) Britton & Rose -- not accepted -- chalk dudleya
  Dudleya rusbyi (Greene) Britton & Rose -- not accepted
  Dudleya saxosa (M.E. Jones) Britton & Rose -- accepted -- Panamint liveforever
  Dudleya saxosa ssp. saxosa (M.E. Jones) Britton & Rose -- accepted -- Panamint dudleya, Panamint liveforever
  Dudleya setchellii (Jeps.) Britton & Rose -- not accepted -- Santa Clara Valley dudleya, Santa Clara Valley liveforever
  Duggena hirsuta (Jacq.) Britton ex Britton & P. Wilson -- not accepted
  Dulichium arundinaceum (L.) Britton -- accepted -- threeway sedge
  Dulichium arundinaceum var. arundinaceum (L.) Britton -- accepted -- three-way sedge
  Duranta arida Britton & P. Wilson -- accepted
  Ebenopsis Britton & Rose -- accepted -- Texas ebony
  Ebenopsis confinis (Standl.) Britton & Rose -- accepted
  Ecastaphyllum ecastaphyllum (L.) Britton -- not accepted
  Eccremocactus Britton & Rose -- not accepted
  Eccremocactus bradei Britton & Rose -- not accepted
  Echinacea paradoxa (J.B.S. Norton) Britton -- accepted -- Bush's purple coneflower
  Echinacea paradoxa var. paradoxa (J.B.S. Norton) Britton -- accepted -- Bush's purple coneflower
  Echinocereus barthelowanus Britton & Rose -- accepted
  Echinocereus caespitosus var. perbellus (Britton & Rose) D. Weniger -- not accepted
  Echinocereus chlorophthalmus (Hook.) Britton & Rose -- not accepted
  Echinocereus fitchii Britton & Rose -- not accepted
  Echinocereus grandis Britton & Rose -- accepted
  Echinocereus luteus Britton & Rose -- not accepted
  Echinocereus mamillatus (Engelm. ex J.M. Coult.) Britton & Rose -- not accepted
  Echinocereus octacanthus (Muehlenpf.) Britton & Rose -- not accepted
  Echinocereus pacificus (Engelm. ex Orcutt) Britton & Rose -- accepted
  Echinocereus palmeri Britton & Rose -- accepted
  Echinocereus palmeri ssp. palmeri Britton & Rose -- accepted
  Echinocereus perbellus Britton & Rose -- not accepted
  Echinocereus reichenbachii ssp. fitchii (Britton & Rose) N.P. Taylor -- not accepted
  Echinocereus reichenbachii ssp. perbellus (Britton & Rose) N.P. Taylor -- not accepted
  Echinocereus reichenbachii ssp. reichenbachii (Terscheck ex Walp.) Britton & Rose -- not accepted
  Echinocereus reichenbachii var. fitchii (Britton & Rose) L.D. Benson -- not accepted -- Fitch's hedgehog cactus
  Echinocereus reichenbachii var. perbellus (Britton & Rose) L.D. Benson -- accepted -- lace hedgehog cactus
  Echinocereus roetteri var. lloydii (Britton & Rose) Backeb. -- not accepted
  Echinocereus sarissophorus Britton & Rose -- not accepted
  Echinocereus scopulorum Britton & Rose -- accepted
  Echinocereus viridiflorus var. standleyi (Britton & Rose) Orcutt ex D. Weniger -- not accepted
  Echinocereus X lloydii Britton & Rose -- not accepted -- Lloyd's hedgehog cactus
  Echinofossulocactus albatus (A. Dietr.) Britton & Rose -- not accepted
  Echinofossulocactus arrigens (Link) Britton & Rose -- not accepted
  Echinofossulocactus confusus Britton & Rose -- not accepted
  Echinofossulocactus dichroacanthus (Mart.) Britton & Rose -- not accepted
  Echinofossulocactus heteracanthus (Muehlenpf.) Britton & Rose -- not accepted
  Echinofossulocactus lamellosus (A. Dietr.) Britton & Rose -- not accepted
  Echinofossulocactus lancifer (A. Dietr.) Britton & Rose -- not accepted
  Echinofossulocactus lloydii Britton & Rose -- not accepted
  Echinofossulocactus pentacanthus (Lem.) Britton & Rose -- not accepted
  Echinofossulocactus tricuspidatus (Scheidw.) Britton & Rose -- not accepted
  Echinofossulocactus violaciflorus (Quehl) Britton & Rose -- not accepted
  Echinofossulocactus zacatecasensis Britton & Rose -- not accepted
  Echinomastus Britton & Rose -- not accepted
  Echinomastus durangensis (Runge) Britton & Rose -- not accepted
  Echinomastus erectocentrus (J.M. Coult.) Britton & Rose -- not accepted
  Echinomastus erectocentrus var. erectocentrus (J.M. Coult.) Britton & Rose -- not accepted
  Echinomastus intertextus (Engelm.) Britton & Rose -- not accepted
  Echinomastus intertextus var. intertextus (Engelm.) Britton & Rose -- not accepted
  Echinomastus unguispinus (Engelm.) Britton & Rose -- not accepted
  Echinopsis aurea Britton & Rose -- accepted
  Echinopsis aurea ssp. aurea Britton & Rose -- accepted
  Echinopsis aurea ssp. shaferi (Britton & Rose) M. Lowry -- accepted
  Echinopsis bruchii (Britton & Rose) Friedrich & Glaetzle -- not accepted
  Echinopsis cuzcoensis (Britton & Rose) H. Friedrich & G.D. Rowley -- accepted
  Echinopsis ferox (Britton & Rose) Backeb. -- accepted
  Echinopsis formosa ssp. bruchii (Britton & Rose) M. Lowry -- accepted
  Echinopsis longispina (Britton & Rose) Werderm. -- not accepted
  Echinopsis pachanoi (Britton & Rose) H. Friedrich & G.D. Rowley -- accepted
  Echinopsis pampana (Britton & Rose) D.R. Hunt -- accepted
  Echinopsis peruviana (Britton & Rose) H. Friedrich & G.D. Rowley -- accepted
  Echinopsis peruviana ssp. peruviana (Britton & Rose) H. Friedrich & G.D. Rowley -- not accepted
  Echinopsis shaferi Britton & Rose -- not accepted
  Echinopsis spegazziniana Britton & Rose -- not accepted
  Echites echites (L.) Britton -- not accepted
  Eleocharis acicularis var. radicans (A. Dietr.) Britton -- not accepted
  Eleocharis coloradoensis (Britton) Gilly -- accepted -- dwarf spikerush
  Eleocharis leptos var. coloradoensis (Britton) Svenson -- not accepted
  Eleocharis macrostachya Britton -- accepted -- pale spikerush
  Eleocharis montevidensis var. parishii (Britton) V.E. Grant -- not accepted
  Eleocharis ovata var. engelmannii (Steud.) Britton -- not accepted
  Eleocharis parishii Britton -- accepted -- Parish spikerush, Parish's spikerush
  Eleocharis parvula var. coloradoensis (Britton) Beetle -- not accepted
  Eleocharis praticola Britton -- not accepted
  Eleocharis ravenelii Britton -- accepted -- Rio Grande spikerush
  Eleocharis shaferi Britton -- not accepted
  Eleocharis smallii Britton -- not accepted -- Small's spikerush
  Eleocharis wolfii (A. Gray) A. Gray ex Britton -- accepted -- wolf's spike-rush, Wolf's spikerush
  Eleocharis yunquensis Britton -- not accepted
  Emelista tora auct. non (L.) Britton & Rose ex Britton & P. Wilson -- not accepted
  Encyclia bifida (Aubl.) Britton & P. Wilson -- not accepted -- thicket butterfly orchid
  Encyclia fucata (Lindl.) Britton & Millsp. -- accepted -- West Indian butterfly orchid
  Encyclia krugii (Bello) Britton & P. Wilson -- not accepted
  Encyclia rufa (Lindl.) Britton & Millsp. -- accepted -- rufous butterfly orchid
  Encyclia sintenisii (Rchb. f.) Britton -- not accepted -- Sintenis' butterfly orchid
  Entadopsis polyphylla (Benth.) Britton -- not accepted
  Epibaterium carolinum (L.) Britton -- not accepted
  Epiphyllanthus candidus (Loefgr.) Britton & Rose -- not accepted
  Epiphyllanthus microsphaericus (K. Schum.) Britton & Rose -- not accepted
  Epiphyllanthus obovatus (Engelm. ex K. Schum.) Britton & Rose -- not accepted
  Epiphyllum cartagense (F.A.C. Weber) Britton & Rose -- accepted
  Epiphyllum caudatum Britton & Rose -- not accepted
  Epiphyllum costaricense (F.A.C. Weber) Britton & Rose -- not accepted
  Epiphyllum darrahii (K. Schum.) Britton & Rose -- not accepted
  Epiphyllum grandilobum (F.A.C. Weber) Britton & Rose -- accepted
  Epiphyllum guatemalense Britton & Rose -- not accepted
  Epiphyllum hookeri ssp. guatemalense (Britton & Rose) Ralf Bauer -- accepted
  Epiphyllum lepidocarpum (F.A.C. Weber) Britton & Rose -- accepted
  Epiphyllum nelsonii Britton & Rose -- not accepted
  Epiphyllum pittieri (F.A.C. Weber) Britton & Rose -- not accepted
  Epiphyllum pumilum Britton & Rose -- accepted
  Epiphyllum stenopetalum (C.F. Först.) Britton & Rose -- not accepted
  Epiphyllum strictum (Lem.) Britton & Rose -- not accepted
  Epiphyllum thomasianum (K. Schum.) Britton & Rose -- accepted
  Epiphyllum thomasianum ssp. thomasianum (K. Schum.) Britton & Rose -- accepted
  Epithelantha A. Weber ex Britton & Rose -- accepted -- pingpong ball cactus
  Epithelantha micromeris (Engelm.) A. Weber ex Britton & Rose -- accepted -- Biznaga-blanca chilona, pingpong ball cactus
  Epithelantha micromeris ssp. micromeris (Engelm.) A. Weber ex Britton & Rose -- not accepted
  Epithelantha micromeris var. micromeris (Engelm.) A. Weber ex Britton & Rose -- not accepted -- pingpong ball cactus
  Eragrostis hypnoides (Lam.) Britton, Sterns & Poggenb. -- accepted -- creeping lovegrass, teal love grass, teal lovegrass
  Erdisia Britton & Rose -- not accepted
  Erdisia meyenii Britton & Rose -- not accepted
  Erdisia philippii (Regel & Schmidt) Britton & Rose -- not accepted
  Erdisia spiniflora (Phil.) Britton & Rose -- not accepted
  Erdisia squarrosa (Vaupel) Britton & Rose -- not accepted
  Erigeron ramosus (Walter) Britton, Sterns & Poggenb. -- not accepted
  Erigeron subtrinervis Rydb. ex Porter & Britton -- accepted -- three-nerve fleabane, threenerve fleabane, threeveined fleabane
  Erigeron subtrinervis var. subtrinervis Rydb. ex Porter & Britton -- not accepted -- threenerve fleabane
  Eriosyce ceratistes (Otto) Britton & Rose -- not accepted
  Ernodea cokeri Britton ex Coker -- accepted -- one-nerved ernodea
  Eroteum albopunctatum (Griseb.) Britton -- not accepted
  Eschenbachia lyrata (Kunth) Britton & Millsp. -- not accepted
  Escobaria Britton & Rose -- accepted -- foxtail cactus, pincushion cactus
  Escobaria bella Britton & Rose -- not accepted
  Escobaria chaffeyi Britton & Rose -- not accepted -- Biznaga-Escobar de Cedros
  Escobaria chihuahuensis Britton & Rose -- accepted
  Escobaria chihuahuensis ssp. chihuahuensis Britton & Rose -- accepted
  Escobaria cubensis (Britton & Rose) D.R. Hunt -- accepted
  Escobaria dasyacantha (Engelm.) Britton & Rose -- accepted -- Big Bend foxtail cactus, Biznaga-Escobar de espinas gruesas
  Escobaria dasyacantha ssp. chaffeyi (Britton & Rose) N.P. Taylor -- accepted
  Escobaria dasyacantha ssp. dasyacantha (Engelm.) Britton & Rose -- accepted
  Escobaria dasyacantha var. chaffeyi (Britton & Rose) N.P. Taylor -- not accepted -- Chaffey's foxtail cactus
  Escobaria dasyacantha var. dasyacantha (Engelm.) Britton & Rose -- not accepted -- Big Bend foxtail cactus
  Escobaria lloydii Britton & Rose -- accepted
  Escobaria runyonii Britton & Rose -- not accepted
  Escobaria sneedii Britton & Rose -- accepted -- carpet foxtail cactus
  Escobaria sneedii ssp. sneedii Britton & Rose -- accepted
  Escobaria sneedii var. sneedii Britton & Rose -- not accepted -- carpet foxtail cactus, Sneed's foxtail cactus
  Escobaria tuberculosa (Engelm.) Britton & Rose -- accepted -- Biznaga-Escobar rómbica, white column foxtail cactus
  Espostoa Britton & Rose -- accepted
  Espostoa lanata (Kunth) Britton & Rose -- accepted
  Espostoa lanata ssp. lanata (Kunth) Britton & Rose -- accepted
  Eubotrys recurva (Buckley) Britton -- accepted -- mountain fetterbush, redtwig doghobble
  Eugenia boqueronensis Britton -- accepted -- Sierra de Cayey stopper
  Eugenia borinquensis Britton -- accepted -- guayabota de sierra
  Eugenia cordzalensis Britton -- not accepted
  Eugenia corozalensis Britton -- accepted -- sperry guava
  Eugenia stewardsonii Britton -- accepted -- Stewardson's stopper
  Eugenia underwoodii Britton -- accepted -- Underwood's stopper
  Eugenia xerophytica Britton -- not accepted -- aridland stopper
  Eulychnia iquiquensis (K. Schum.) Britton & Rose -- accepted
  Eulychnia iquiquensis ssp. iquiquensis (K. Schum.) Britton & Rose -- accepted
  Eupatorium borinquense (Britton) B.L. Rob. -- not accepted -- limestone thoroughwort
  Eupatorium dolicholepis (Urb.) Britton -- not accepted -- oreganillo
  Eupatorium petaloideum Britton ex Small -- accepted -- snowy white thoroughwort
  Eupatorium rotundifolium var. saundersii (Porter ex Britton) Cronquist -- not accepted
  Euphorbia cowellii (Millsp. ex Britton) Oudejans -- accepted -- Cowell's sandmat
  Euphorbia tithymaloides ssp. jamaicensis (Millsp. & Britton) V.W. Steinm. -- accepted
  Euthamia caroliniana (L.) Greene ex Porter & Britton -- not accepted
  Euthamia leptocephala (Torr. & A. Gray) Greene ex Porter & Britton -- accepted -- bushy goldentop
  Evolvulus squamosus Britton -- accepted -- rockyplains dwarf morning-glory
  Exogonium solanifolium (L.) Britton -- not accepted
  Exostema sanctae-luciae (Kentish) Britton -- accepted -- Jamaicanbark
  Facheiroa Britton & Rose -- accepted
  Facheiroa pubiflora Britton & Rose -- not accepted
  Ferocactus Britton & Rose -- accepted -- barrel cactus
  Ferocactus acanthodes (Lem.) Britton & Rose -- not accepted
  Ferocactus acanthodes var. acanthodes (Lem.) Britton & Rose -- not accepted -- viznaga
  Ferocactus alamosanus (Britton & Rose) Britton & Rose -- accepted
  Ferocactus alamosanus ssp. alamosanus (Britton & Rose) Britton & Rose -- accepted
  Ferocactus chrysacanthus (Orcutt) Britton & Rose -- accepted
  Ferocactus chrysacanthus ssp. chrysacanthus (Orcutt) Britton & Rose -- accepted
  Ferocactus covillei Britton & Rose -- not accepted
  Ferocactus crassihamatus (F.A.C. Weber) Britton & Rose -- not accepted
  Ferocactus diguetii (F.A.C. Weber) Britton & Rose -- accepted
  Ferocactus echidne (DC.) Britton & Rose -- accepted
  Ferocactus emoryi ssp. covillei (Britton & Rose) D.R. Hunt & Dimmitt -- accepted
  Ferocactus flavovirens (Scheidw.) Britton & Rose -- accepted
  Ferocactus fordii (Orcutt) Britton & Rose -- accepted
  Ferocactus fordii ssp. fordii (Orcutt) Britton & Rose -- accepted
  Ferocactus glaucescens (DC.) Britton & Rose -- accepted
  Ferocactus haematacanthus (Muehlenpf.) Britton & Rose -- accepted
  Ferocactus hamatacanthus (Muehlenpf.) Britton & Rose -- accepted -- Biznaga-barril costillona, Turk's head
  Ferocactus hamatacanthus ssp. hamatacanthus (Muehlenpf.) Britton & Rose -- accepted
  Ferocactus hamatacanthus var. hamatacanthus (Muehlenpf.) Britton & Rose -- not accepted -- Turk's head
  Ferocactus johnsonii (Parry ex Engelm.) Britton & Rose -- not accepted
  Ferocactus johnstonianus Britton & Rose -- accepted
  Ferocactus latispinus (Haw.) Britton & Rose -- accepted
  Ferocactus latispinus ssp. latispinus (Haw.) Britton & Rose -- accepted
  Ferocactus lecontei (Engelm.) Britton & Rose -- not accepted -- Biznaga-barril de Gila
  Ferocactus macrodiscus (Mart.) Britton & Rose -- accepted
  Ferocactus macrodiscus ssp. macrodiscus (Mart.) Britton & Rose -- accepted
  Ferocactus peninsulae (F.A.C. Weber) Britton & Rose -- accepted
  Ferocactus peninsulae ssp. santa-maria (Britton & Rose) Pilbeam & Bowdery -- not accepted
  Ferocactus robustus (Link & Otto) Britton & Rose -- accepted
  Ferocactus santa-maria Britton & Rose -- accepted
  Ferocactus townsendianus Britton & Rose -- accepted
  Ferocactus townsendianus var. santa-maria (Britton & Rose) G.E. Linds. -- not accepted
  Ferocactus townsendianus var. santamaria (Britton & Rose) G.E. Linds. -- not accepted
  Ferocactus uncinatus (Galeotti ex Pfeiff.) Britton & Rose -- not accepted
  Ferocactus viridescens (Torr. & A. Gray) Britton & Rose -- accepted -- Biznaga-barril verdosa, coast barrel cactus, San Diego barrel cactus
  Ferocactus wislizeni (Engelm.) Britton & Rose -- accepted -- Biznaga-barril de Nuevo México, candy barrel cactus, fishhook barrel cactus
  Ferocactus wislizenii (Engelm.) Britton & Rose -- not accepted
  Filago prolifera (Nutt. ex DC.) Britton non Pomel -- not accepted
  Fimbristylis castanea var. puberula (Michx.) Britton -- not accepted
  Fimbristylis curassavica (Britton) Alain -- not accepted
  Fimbristylis harperi Britton ex Small -- not accepted
  Fimbristylis harrisii (Britton) C.D. Adams -- not accepted -- Harris' fimbry
  Fimbristylis inaguensis Britton -- accepted -- Bahama fimbry
  Fimbristylis interior Britton -- not accepted
  Fimbristylis perpusilla R.M. Harper ex Small & Britton -- accepted -- Harper's fimbry
  Fimbristylis portoricensis (Britton) Alain -- not accepted
  Fimbristylis puberula var. interior (Britton) Kral -- accepted -- hairy fimbry
  Fragaria americana (Porter) Britton -- not accepted
  Frailea Britton & Rose -- accepted
  Frailea caespitosa (Speg.) Britton & Rose -- not accepted
  Frailea cataphracta (Dams) Britton & Rose -- accepted
  Frailea cataphracta ssp. cataphracta (Dams) Britton & Rose -- not accepted
  Frailea gracillima (Lem.) Britton & Rose -- accepted
  Frailea gracillima ssp. gracillima (Lem.) Britton & Rose -- accepted
  Frailea grahliana (F. Haage) Britton & Rose -- not accepted
  Frailea grahliana ssp. grahliana (F. Haage) Britton & Rose -- not accepted
  Frailea knippeliana (Quehl) Britton & Rose -- not accepted
  Frailea pumila (Lem.) Britton & Rose -- accepted
  Frailea pumila ssp. pumila (Lem.) Britton & Rose -- not accepted
  Frailea pygmaea (Speg.) Britton & Rose -- accepted
  Frailea pygmaea ssp. pygmaea (Speg.) Britton & Rose -- accepted
  Frailea schilinzkyana (F. Haage ex K. Schum.) Britton & Rose -- accepted
  Frailea schilinzkyana ssp. schilinzkyana (F. Haage ex K. Schum.) Britton & Rose -- accepted
  Fraxinus campestris Britton -- not accepted
  Fraxinus darlingtonii Britton -- not accepted
  Fraxinus michauxii Britton -- not accepted
  Fraxinus smallii Britton -- not accepted
  Fraxinus velutina var. toumeyi (Britton) Rehder -- not accepted
  Gaertneria acanthicarpa (Hook.) Britton -- not accepted
  Gaillardia suavis (A. Gray & Engelm.) Britton & Rusby -- accepted -- perfumeballs, sweet gaillardia
  Galactia regularis (L.) Britton, Sterns & Poggenb. -- accepted -- eastern milkpea
  Galactia volubilis (L.) Britton -- accepted -- downy milkpea
  Galatea bulbosa (Mill.) Britton -- not accepted
  Galium circaezans var. glabellum Britton -- not accepted
  Galium circaezans var. glabrum Britton -- not accepted
  Galium kamtschaticum var. oreganum (Britton) Piper -- not accepted
  Galium latifolium var. hispidifolium Small ex Britton -- not accepted
  Galium oreganum Britton -- accepted -- Oregon bedstraw
  Galium peregrina Britton, Sterns & Poggenb. -- not accepted
  Galium peregrinum Britton, Sterns & Poggenb. -- not accepted
  Galpinsia hartwegii (Benth.) Britton -- not accepted
  Garcia mayana Britton -- not accepted
  Garcinia hessii (Britton) Alain -- accepted -- lemon saptree
  Gaumerocassia ekmaniana (Urb.) Britton ex Britton & Rose -- not accepted
  Geranium bicknellii Britton -- accepted -- Bicknell's cranesbill, northern crane's-bill
  Geranium bicknellii var. bicknellii Britton -- not accepted -- Bicknell's cranesbill
  Geranium nemorale var. bicknellii (Britton) Fernald -- not accepted
  Gerardia besseyana Britton -- not accepted
  Gerardia paupercula (A. Gray) Britton -- not accepted
  Gerardia portoricensis Britton & P. Wilson -- not accepted
  Gerardia virginica (L.) Britton, Sterns & Poggenb. -- not accepted
  Gesneria clarensis Britton & P. Wilson -- accepted
  Gesneria earlei Urb. & Britton -- accepted
  Gesneria jamaicensis Britton -- accepted
  Gesneria leiocarpa Urb. & Britton -- not accepted
  Gesneria nipensis Britton & P. Wilson -- not accepted
  Gesneria purpurascens var. yamuriensis (Britton & P. Wilson) Borhidi -- not accepted
  Gesneria yamuriensis Britton & P. Wilson -- not accepted
  Ghinia spinosa (Sw.) Britton & P. Wilson -- not accepted
  Gilia acerosa (A. Gray) Britton -- not accepted
  Glabraria geniculata (Walter) Britton -- not accepted
  Glossoloma bolivianum (Britton ex Rusby) J.L. Clark -- accepted
  Glycine priceana (B.L. Rob.) Britton -- not accepted
  Gnaphalium helleri Britton -- not accepted
  Gnaphalium helleri var. helleri Britton -- not accepted -- Heller's cudweed
  Gnaphalium obtusifolium var. helleri (Britton) S.F. Blake -- not accepted
  Gormania debilis (S. Watson) Britton -- not accepted
  Gormania eastwoodiae Britton -- not accepted
  Gormania laxa Britton -- not accepted
  Gormania obtusata (A. Gray) Britton -- not accepted
  Gormania oregana (Nutt.) Britton -- not accepted
  Gormania watsonii Britton -- not accepted
  Grossularia amara (McClatchie) Coville & Britton -- not accepted
  Grossularia binominata (A. Heller) Coville & Britton -- not accepted
  Grossularia californica (Hook. & Arn.) Coville & Britton -- not accepted
  Grossularia cognata (Greene) Coville & Britton -- not accepted
  Grossularia cruenta (Greene) Coville & Britton -- not accepted
  Grossularia curvata (Small) Coville & Britton -- not accepted
  Grossularia divaricata (Douglas) Coville & Britton -- not accepted
  Grossularia greeneana (A. Heller) Coville & Britton -- not accepted
  Grossularia greeneiana (A. Heller) Coville & Britton -- not accepted
  Grossularia hesperia (McClatchie) Coville & Britton -- not accepted
  Grossularia hystrix (Eastw.) Coville & Britton -- not accepted
  Grossularia inermis (Rydb.) Coville & Britton -- not accepted
  Grossularia irrigua (Douglas) Coville & Britton -- not accepted
  Grossularia lasiantha (Greene) Coville & Britton -- not accepted
  Grossularia lobbii (A. Gray) Coville & Britton -- not accepted
  Grossularia marshallii (Greene) Coville & Britton -- not accepted
  Grossularia menziesii (Pursh) Coville & Britton -- not accepted
  Grossularia missouriensis (Nutt.) Coville & Britton -- not accepted
  Grossularia parishii (A. Heller) Coville & Britton -- not accepted
  Grossularia quercetora (Greene) Coville & Britton -- not accepted
  Grossularia quercetorum (Greene) Coville & Britton -- not accepted
  Grossularia roezlii (Regel) Coville & Britton -- not accepted
  Grossularia rotundifolia (Michx.) Coville & Britton -- not accepted
  Grossularia sericea (Eastw.) Coville & Britton -- not accepted
  Grossularia setosa (Lindl.) Coville & Britton -- not accepted
  Grossularia speciosa (Pursh) Coville & Britton -- not accepted
  Grossularia velutina (Greene) Coville & Britton -- not accepted
  Grossularia victoris (Greene) Coville & Britton -- not accepted
  Grossularia watsoniana (Koehne) Coville & Britton -- not accepted
  Grusonia Rchb. f. ex Britton & Rose -- accepted
  Grusonia bradtiana (J.M. Coult.) Britton & Rose -- accepted
  Guapira bracei (Britton) Little -- not accepted
  Guapira floridana (Britton) Lundell -- not accepted
  Guilandina culebrae Britton & P. Wilson -- accepted
  Guilandina divergens (Urb.) Britton -- not accepted
  Guilandina ovalifolia (Urb.) Britton -- not accepted
  Guilandina portoricensis Britton & P. Wilson -- accepted
  Gundlachia corymbosa (Urb.) Britton ex Boldingh -- accepted -- yambush
  Gutierrezia sarothrae (Pursh) Britton & Rusby -- accepted -- broom snakeweed, broomweed, perennial snakeweed, stinkweed, turpentine weed, yellow top
  Gymnocalycium anisitsii (K. Schum.) Britton & Rose -- accepted
  Gymnocalycium anisitsii ssp. anisitsii (K. Schum.) Britton & Rose -- accepted
  Gymnocalycium brachyanthum (Gürke) Britton & Rose -- not accepted
  Gymnocalycium damsii (K. Schum.) Britton & Rose -- not accepted
  Gymnocalycium guerkeanum (Heese) Britton & Rose -- not accepted
  Gymnocalycium hyptiacanthum (Lem.) Britton & Rose -- not accepted
  Gymnocalycium joossensianum (Boed.) Britton & Rose -- not accepted
  Gymnocalycium kurtzianum (Gürke) Britton & Rose -- not accepted
  Gymnocalycium leeanum (Hook.) Britton & Rose -- not accepted
  Gymnocalycium megalothelon (Sencke) Britton & Rose -- not accepted
  Gymnocalycium melanocarpum (Arechav.) Britton & Rose -- not accepted
  Gymnocalycium mihanovichii (Fric & Gürke) Britton & Rose -- accepted
  Gymnocalycium monvillei (Lem.) Pfeiff. ex Britton & Rose -- accepted
  Gymnocalycium monvillei ssp. monvillei (Lem.) Pfeiff. ex Britton & Rose -- accepted
  Gymnocalycium mostii (Gürke) Britton & Rose -- accepted
  Gymnocalycium multiflorum (Hook.) Britton & Rose -- not accepted
  Gymnocalycium netrelianum (Monv.) Britton & Rose -- not accepted
  Gymnocalycium platense (Speg.) Britton & Rose -- not accepted
  Gymnocalycium saglione (F. Cels) Britton & Rose -- not accepted
  Gymnocalycium saglionis (F. Cels) Britton & Rose -- accepted
  Gymnocalycium saglionis ssp. saglionis (F. Cels) Britton & Rose -- not accepted
  Gymnocalycium schickendantzii (F.A.C. Weber) Britton & Rose -- accepted
  Gymnocalycium schickendantzii ssp. schickendantzii (F.A.C. Weber) Britton & Rose -- accepted
  Gymnocalycium spegazzinii Britton & Rose -- accepted
  Gymnocalycium spegazzinii ssp. spegazzinii Britton & Rose -- accepted
  Gymnocalycium stuckertii (Speg.) Britton & Rose -- not accepted
  Gymnocalycium uruguayense (Arechav.) Britton & Rose -- accepted
  Gymnopogon ambiguus (Michx.) Britton, Sterns & Poggenb. -- accepted -- bearded skeletongrass
  Hamatocactus Britton & Rose -- not accepted
  Harrisia Britton -- accepted -- applecactus
  Harrisia aboriginum Small ex Britton & Rose -- accepted -- aboriginal pricklyapple, prickly applecactus
  Harrisia adscendens (Gürke) Britton & Rose -- accepted
  Harrisia bonplandii (J. Parm. & Pfeiff.) Britton & Rose -- not accepted
  Harrisia brookii Britton -- accepted
  Harrisia earlei Britton & Rose -- accepted
  Harrisia eriophora (Pfeiff.) Britton -- accepted
  Harrisia fernowii Britton -- accepted
  Harrisia fragrans Small ex Britton & Rose -- accepted -- Caribbean applecactus
  Harrisia gracilis (Mill.) Britton -- accepted
  Harrisia martinii (Labour.) Britton -- accepted -- mooncactus
  Harrisia nashii Britton -- accepted
  Harrisia pomanensis (F.A.C. Weber ex K. Schum.) Britton & Rose -- accepted -- applecactus
  Harrisia pomanensis ssp. pomanensis (F.A.C. Weber ex K. Schum.) Britton & Rose -- not accepted
  Harrisia portoricensis Britton -- accepted -- higo chumbo, Puerto Rico applecactus
  Harrisia simpsonii Small ex Britton & Rose -- accepted -- Simpson's applecactus
  Harrisia taylorii Britton -- accepted
  Harrisia tortuosa (J. Forbes ex Otto & A. Dietr.) Britton & Rose -- accepted
  Hatiora Britton & Rose -- accepted
  Hatiora bambusoides (F.A.C. Weber) Britton & Rose -- not accepted
  Hatiora cylindrica Britton & Rose -- accepted
  Hatiora salicornioides (Haw.) Britton & Rose -- accepted
  Havardia mexicana (Rose) Britton & Rose -- accepted
  Havardia pallens (Benth.) Britton & Rose -- accepted -- haujillo
  Havardia sonorae (S. Watson) Britton & Rose -- accepted
  Hedyotis croftiae (Britton & Rusby) Shinners -- not accepted
  Hedysarum americanum (Michx. ex Pursh) Britton -- not accepted
  Helenium setigerum (DC.) Britton & Rusby -- not accepted
  Helianthemum nashii Britton -- accepted -- Florida scrub frostweed
  Helianthium tenellum (Mart.) Britton -- not accepted
  Helianthocereus grandiflorus (Britton & Rose) Backeb. -- not accepted
  Helianthus canus (Britton) Woot. & Standl. -- not accepted
  Helianthus dalyi Britton -- not accepted
  Helianthus giganteus var. subtuberosus Britton -- not accepted
  Helianthus nuttallii ssp. rydbergii (Britton) R.W. Long -- accepted -- Rydberg's sunflower
  Helianthus nuttallii var. rydbergii (Britton) B. Boivin -- not accepted
  Helianthus nuttallii var. subtuberosus (Britton) B. Boivin -- not accepted
  Helianthus rydbergii Britton -- not accepted
  Helianthus scrophulariifolius Britton -- not accepted
  Helianthus subtuberosus (Britton) Britton -- not accepted
  Helianthus X ambiguus (A. Gray) Britton (pro sp.) -- accepted -- ambiguous sunflower
  Helianthus X kellermanii Britton (pro sp.) -- accepted -- Kellerman's sunflower
  Heliocereus (A. Berger) Britton & Rose -- not accepted
  Heliocereus cinnabarinus (Weing.) Britton & Rose -- not accepted
  Heliocereus elegantissimus Britton & Rose -- not accepted
  Heliocereus schrankii (Zucc. ex Seitz) Britton & Rose -- not accepted
  Heliocereus speciosus (Cav.) Britton & Rose -- not accepted
  Hepatica acuta (Pursh) Britton -- not accepted
  Heterosavia bahamensis (Britton) Petra Hoffm. -- accepted -- Bahama maidenbush
  Heterotheca subaxillaris (Lam.) Britton & Rusby -- accepted -- camphorweed, golden aster
  Heterotheca subaxillaris ssp. subaxillaris (Lam.) Britton & Rusby -- accepted
  Hibiscus oculiroseus Britton -- not accepted
  Hicoria alba Britton -- not accepted
  Hicoria aquatica (F. Michx.) Britton -- not accepted
  Hicoria cordiformis (Wangenh.) Britton -- not accepted
  Hicoria glabra (Mill.) Britton -- not accepted
  Hicoria myristiciformis (F. Michx.) Britton -- not accepted
  Hicoria ovata (Mill.) Britton -- not accepted
  Hicoria pecan (Marsh.) Britton -- not accepted
  Hieracium greenii Porter & Britton -- not accepted -- Maryland hawkweed
  Hieracium X alleghaniense Britton (pro sp.) -- accepted -- Allegheny hawkweed
  Hipposelinum levisticum (L.) Britton & Rose -- not accepted
  Hoffmannseggia peninsularis (Britton) Wiggins -- accepted
  Hohenbergia attenuata Britton -- accepted -- longtip lacebark
  Homalobus tenellus (Pursh) Britton -- not accepted
  Homalocenchrus virginicus (Willd.) Britton -- not accepted
  Homalocephala Britton & Rose -- not accepted
  Homalocephala texensis (Hopffer) Britton & Rose -- not accepted
  Houstonia croftiae Britton & Rusby -- accepted -- Croft's bluet
  Houstonia lanceolata (Poir.) Britton -- not accepted
  Houstonia purpurea var. pubescens Britton -- not accepted
  Hyalocereus (A. Berger) Britton & Rose -- not accepted
  Hyalocereus lemairei (Hook.) Britton & Rose -- not accepted
  Hyalocereus undatus (Haw.) Britton & Rose -- not accepted
  Hylocereus (A. Berger) Britton & Rose -- accepted -- nightblooming cactus
  Hylocereus antiguensis Britton & Rose -- not accepted
  Hylocereus calcaratus (F.A.C. Weber) Britton & Rose -- accepted
  Hylocereus costaricensis (F.A.C. Weber) Britton & Rose -- accepted -- Costa Rica nightblooming cactus
  Hylocereus cubensis Britton & Rose -- not accepted
  Hylocereus extensus (Salm-Dyck ex DC.) Britton & Rose ex Rose -- accepted
  Hylocereus guatemalensis (Eichlam) Britton & Rose -- accepted
  Hylocereus lemairei (Hook.) Britton & Rose -- not accepted
  Hylocereus minutiflorus Britton & Rose -- accepted
  Hylocereus monacanthus (Lem.) Britton & Rose -- accepted -- nightblooming cereus
  Hylocereus napoleonis (Graham) Britton & Rose -- not accepted
  Hylocereus ocamponis (Salm-Dyck) Britton & Rose -- accepted
  Hylocereus polyrhizus (F.A.C. Weber) Britton & Rose -- not accepted
  Hylocereus purpusii (Weing.) Britton & Rose -- not accepted
  Hylocereus stenopterus (F.A.C. Weber) Britton & Rose -- accepted
  Hylocereus triangularis (L.) Britton & Rose -- accepted
  Hylocereus undatus (Haw.) Britton & Rose -- accepted -- nightblooming cactus, Pitahaya orejona
  Hylocereus venezuelensis Britton & Rose -- not accepted
  Hymenorebutia aurea (Britton & Rose) F. Ritter -- not accepted
  Hypericum boreale (Britton) E.P. Bicknell -- not accepted -- northern St. Johnswort
  Hypericum denticulatum var. ovalifolium (Britton) S.F. Blake -- not accepted
  Hypericum gentianoides (L.) Britton, Sterns & Poggenb. -- accepted -- orangegrass, pinweed St. Johnswort
  Hypericum majus (A. Gray) Britton -- accepted -- greater Canadian St. John's-wort, large St. Johnswort
  Hypericum mutilum ssp. boreale (Britton) J.M. Gillett -- accepted -- northern St. Johnswort
  Hypochaeris chillensis (Kunth) Britton -- accepted -- Brazilian cat's ear, Tweedy's cat's ear
  Icacorea glauciflora (Urb.) Britton -- not accepted
  Icacorea guadalupensis (Duchass. ex Griseb.) Britton ex P. Wilson -- not accepted
  Icacorea luquillensis Britton -- not accepted
  Ilex arimensis (Loes.) Britton ex R.O. Williams -- accepted
  Ilex bronxensis Britton -- not accepted
  Ilex cookii Britton & P. Wilson -- accepted -- Cook's holly
  Ilex montana var. mollis (A. Gray) Britton -- not accepted
  Ilex sintenisii (Urb.) Britton -- not accepted -- Sintenis' holly
  Inga inga (L.) Britton -- not accepted
  Ionidium portoricense (Urb.) Krug & Urb. ex Britton & P. Wilson -- not accepted
  Iris georgiana Britton -- not accepted
  Isandrina emarginata (L.) Britton & Rose -- not accepted
  Isanthus brachiatus (L.) Britton, Sterns & Poggenb. -- not accepted -- false pennyroyal, fluxweed
  Isoetes appalachiana D.F. Brunt. & D.M. Britton -- not accepted -- Appalachian quillwort
  Isoetes junciformis D.F. Brunt. & D.M. Britton -- accepted -- rush quillwort
  Isoetes melanopoda ssp. silvatica D.F. Brunt. & D.M. Britton -- accepted -- blackfoot quillwort
  Isoetes prototypus D.M. Britton -- accepted -- spike quillwort
  Isoetes X echtuckeri D.F. Brunt. & D.M. Britton -- accepted
  Isoetes X jeffreyi D.M. Britton & D.F. Brunt. -- accepted -- Jeffrey's quillwort
  Isoetes X novae-angliae D.F. Brunt. & D.M. Britton -- accepted
  Isoetes X pseudotruncata D.M. Britton & D.F. Brunt. -- accepted
  Isoloma sprucei Britton ex Rusby -- not accepted
  Jacquemontia cayensis Britton -- accepted -- sandyplain clustervine
  Jacquemontia subsalina Britton -- not accepted
  Jacquiniella teretifolia (Sw.) Britton & P. Wilson -- accepted -- Jacquiniella carnosa, moss tufted orchid
  Jasminocereus Britton & Rose -- accepted
  Jasminocereus galapagensis (F.A.C. Weber) Britton & Rose -- not accepted
  Juniperus lucayana auct. non Britton -- not accepted
  Justicia borinquensis Britton -- not accepted -- Monte Cerrote water-willow
  Kneiffia allenii (Britton) Small -- not accepted
  Koellia hyssopifolia (Benth.) Britton -- not accepted
  Koellia pilosa (Nutt.) Britton -- not accepted
  Kohleria sprucei (Britton ex Rusby) Fritsch -- not accepted
  Krainzia longiflora (Britton & Rose) Backeb. -- not accepted
  Krameria imparata (J.F. Macbr.) Britton -- not accepted
  Lacinaria smallii Britton -- not accepted
  Lactuca spicata var. integrifolia (Torr. & A. Gray) Britton -- not accepted
  Lactuca steelei Britton -- not accepted
  Lagenocarpus portoricensis Britton -- not accepted
  Lantana arida Britton -- not accepted
  Lantana bahamensis auct. non Britton -- not accepted
  Lantana ovatifolia auct. non Britton. -- not accepted
  Lappula texana (Scheele) Britton -- not accepted
  Larrea wootonii Britton -- not accepted -- Wooton's holdback
  Lathyrus arizonicus Britton -- not accepted
  Lathyrus lanszwertii var. arizonicus (Britton) S.L. Welsh -- not accepted
  Lauro-cerasus myrtifolia (L.) Britton -- not accepted
  Laurocerasus myrtifolia (L.) Britton -- not accepted
  Lavauxia brachycarpa (A. Gray) Britton -- not accepted
  Lavauxia watsonii (Britton) Small -- not accepted
  Leavenworthia uniflora (Michx.) Britton -- accepted -- Michaux's gladecress
  Lebretonia paniculata (Cav.) Britton -- not accepted
  Lechea divaricata Shuttlw. ex Britton -- accepted -- drysand pinweed
  Lechea intermedia Legg. ex Britton -- accepted -- largepod pinweed
  Lechea intermedia var. intermedia Legg. ex Britton -- accepted -- largepod pinweed
  Lechea leggettii Britton & Hollick -- not accepted
  Lechea maritima Legg. ex Britton, Sterns & Poggenb. -- accepted -- beach pinweed
  Lechea maritima var. maritima Legg. ex Britton, Sterns & Poggenb. -- accepted -- beach pinweed
  Lechea minor var. maritima (Legg. ex Britton, Sterns & Poggenb.) A. Gray -- not accepted
  Lechea tripetala (Moc. & Sessé ex Dunal) Britton -- accepted -- threepetal pinweed
  Legousia perfoliata (L.) Britton -- not accepted
  Leiphaimos portoricensis Britton -- not accepted
  Lemaireocereus Britton & Rose -- not accepted
  Lemaireocereus aragonii (F.A.C. Weber) Britton & Rose -- not accepted
  Lemaireocereus beneckei (Ehrenb.) Britton & Rose -- not accepted
  Lemaireocereus cartwrightianus Britton & Rose -- not accepted
  Lemaireocereus chende (Rol.-Goss.) Britton & Rose -- not accepted
  Lemaireocereus chichipe (Rol.-Goss.) Britton & Rose -- not accepted
  Lemaireocereus deficiens (Otto & A. Dietr.) Britton & Rose -- not accepted
  Lemaireocereus eichlamii Britton & Rose -- not accepted
  Lemaireocereus godingianus Britton & Rose -- not accepted
  Lemaireocereus griseus (Haw.) Britton & Rose -- not accepted
  Lemaireocereus hollianus (F.A.C. Weber) Britton & Rose -- not accepted
  Lemaireocereus hystrix (Haw.) Britton & Rose -- not accepted
  Lemaireocereus laetus (Kunth) Britton & Rose -- not accepted
  Lemaireocereus longispinus Britton & Rose -- not accepted
  Lemaireocereus mixtecensis (J.A. Purpus) Britton & Rose -- not accepted
  Lemaireocereus montanus Britton & Rose -- not accepted
  Lemaireocereus pruinosus (Otto ex Pfeiff.) Britton & Rose -- not accepted
  Lemaireocereus stellatus (Pfeiff.) Britton & Rose -- not accepted
  Lemaireocereus thurberi (Engelm.) Britton & Rose -- not accepted
  Lemaireocereus weberi (J.M. Coult.) Britton & Rose -- not accepted
  Lendneria verticillata (Mill.) Britton -- not accepted
  Leocereus Britton & Rose -- accepted
  Leocereus bahiensis Britton & Rose -- accepted
  Leocereus glaziovii (K. Schum.) Britton & Rose -- not accepted
  Leocereus melanurus (K. Schum.) Britton & Rose -- not accepted
  Leontodon erythrospermum (Andrz. ex Besser) Britton -- not accepted
  Leontodon latiloba (DC.) Britton -- not accepted
  Lepidocoryphantha macromeris ssp. runyonii (Britton & Rose) Doweld -- not accepted
  Lepidocoryphantha runyonii (Britton & Rose) Backeb. -- not accepted
  Lepismium bolivianum (Britton) Barthlott -- not accepted
  Lepismium crenatum (Britton) Barthlott -- not accepted
  Lepismium pittieri (Britton & Rose) Backeb. -- not accepted
  Leptilon canadense (L.) Britton -- not accepted
  Leptilon chinense (Jacq.) Britton -- not accepted
  Leptilon pusillum (Nutt.) Britton -- not accepted
  Leptocereus (A. Berger) Britton & Rose -- accepted
  Leptocereus arboreus Britton & Rose -- accepted
  Leptocereus assurgens (C. Wright ex Griseb.) Britton & Rose -- accepted
  Leptocereus grantianus Britton -- accepted -- sebucan
  Leptocereus leonii Britton & Rose -- accepted
  Leptocereus maxonii Britton & Rose -- not accepted
  Leptocereus prostratus Britton & Rose -- not accepted
  Leptocereus quadricostatus (Bello) Britton & Rose -- accepted -- pitahaya
  Leptocereus sylvestris Britton & Rose -- accepted
  Leptocereus weingartianus (E. Hartmann in Dams) Britton & Rose -- accepted
  Leptoglottis angustisiliqua Britton & Rose -- not accepted
  Leptoglottis chapmanii Small ex Britton & Rose -- not accepted
  Leptoglottis floridana (Chapm.) Small ex Britton & Rose -- not accepted
  Leptoglottis hystricina Small ex Britton & Rose -- not accepted
  Leptoglottis microphylla (Dryand.) Britton & Rose -- not accepted
  Leptoglottis nelsonii Britton & Rose -- not accepted
  Leptoglottis nuttallii DC. ex Britton & Rose -- not accepted
  Leptoglottis occidentalis (Wooton & Standl.) Britton & Rose -- not accepted
  Lespedeza angustifolia var. brevifolia Britton -- not accepted
  Lespedeza intermedia (S. Watson) Britton -- not accepted
  Lespedeza prairea (Mack. & Bush) Britton -- not accepted
  Lespedeza stuevei var. angustifolia Britton -- not accepted
  Lespedeza texana Britton -- accepted -- Texas lespedeza
  Lespedeza virginica (L.) Britton -- accepted -- slender lespedeza
  Lespedeza X oblongifolia (Britton) W. Stone -- accepted -- oblong lespedeza
  Lesquerella engelmannii ssp. ovalifolia (Rydb. ex Britton) C. Clark -- not accepted
  Levenworthia uniflora (Michx.) Britton -- not accepted
  Liatris graminifolia var. smallii (Britton) Fernald & Grisc. -- not accepted
  Liatris kansana Britton -- not accepted
  Ligusticum canadense (L.) Britton -- accepted -- Canadian licorice-root
  Limonium carolinianum (Walter) Britton -- accepted -- American thrift, canker root, Carolina sea lavender, Carolina sealavender, lavender thrift, seaside thrift
  Lindernia verticillata (Mill.) Britton -- not accepted
  Linum medium (Planch.) Britton -- accepted -- stiff yellow flax
  Linum medium var. medium (Planch.) Britton -- accepted -- stiff yellow flax
  Lippia alba (Mill.) N.E. Br. ex Britton & P. Wilson -- accepted -- bushy lippia, white lippia
  Lippia helleri Britton -- not accepted
  Lippia ligustrina (Lag.) Britton -- not accepted
  Lippia micromera var. helleri (Britton) Moldenke -- accepted -- Spanish thyme
  Lobivia Britton & Rose -- not accepted
  Lobivia andalgalensis (F.A.C. Weber ex K. Schum.) Britton & Rose -- not accepted
  Lobivia aurea (Britton & Rose) Backeb. -- not accepted
  Lobivia boliviensis Britton & Rose -- not accepted
  Lobivia bruchii Britton & Rose -- not accepted
  Lobivia cachensis (Speg.) Britton & Rose -- not accepted
  Lobivia caespitosa (J.A. Purpus) Britton & Rose -- not accepted
  Lobivia chionanthus (Speg.) Britton & Rose -- not accepted
  Lobivia cinnabarina (Hook.) Britton & Rose -- not accepted
  Lobivia corbula (Herrera) Britton & Rose -- not accepted
  Lobivia cumingii (Hopffer) Britton & Rose -- not accepted
  Lobivia famatimensis (Speg.) Britton & Rose -- not accepted
  Lobivia ferox Britton & Rose -- not accepted
  Lobivia formosa ssp. bruchii (Britton & Rose) Rausch -- not accepted
  Lobivia formosa ssp. grandis (Britton & Rose) Rausch -- not accepted
  Lobivia formosa var. bruchii (Britton & Rose) Rausch -- not accepted
  Lobivia formosa var. grandis (Britton & Rose) Rausch -- not accepted
  Lobivia grandiflora Britton & Rose -- not accepted
  Lobivia grandis Britton & Rose -- not accepted
  Lobivia haematantha (Speg.) Britton & Rose -- not accepted
  Lobivia lateritia (Gürke) Britton & Rose -- not accepted
  Lobivia longispina Britton & Rose -- not accepted
  Lobivia pampana Britton & Rose -- not accepted
  Lobivia pentlandii (Hook.) Britton & Rose -- not accepted
  Lobivia saltensis (Speg.) Britton & Rose -- not accepted
  Lobivia shaferi Britton & Rose -- not accepted
  Lobivia thionantha (Speg.) Britton & Rose -- not accepted
  Lophocereus (Engelm.) Britton & Rose -- not accepted
  Lophocereus sargentianus (Orcutt) Britton & Rose -- not accepted
  Lophocereus schottii (Engelm.) Britton & Rose -- not accepted -- Senita
  Lotus helleri Britton -- not accepted
  Lotus mearnsii (Britton) Greene -- not accepted -- Mearns' bird's-foot trefoil
  Lotus mearnsii var. mearnsii (Britton) Greene -- not accepted -- Mearns' bird's-foot trefoil
  Lotus purshianus var. helleri (Britton) Isely -- not accepted
  Lotus unifoliolatus var. helleri (Britton) Kartesz & Gandhi -- not accepted -- Heller's bird's-foot trefoil
  Ludwigia alternifolia var. linearifolia Britton -- not accepted
  Ludwigiantha brevipes Long ex Britton, A. Braun & Small -- not accepted
  Luetkea caespitosa (Nutt.) Britton -- not accepted
  Luetkea caespitosa var. elatior (S. Watson) Britton -- not accepted
  Lycopus amplectens var. pubens (Britton) Fernald -- not accepted
  Lycopus pubens Britton -- not accepted
  Lysiloma microphylla var. thornberi (Britton & Rose) Isely -- not accepted
  Lysiloma microphyllum var. thornberi (Britton & Rose) Isely -- not accepted
  Lysiloma thornberi Britton & Rose -- not accepted
  Lysimachia terrestris (L.) Britton, Sterns & Poggenb. -- accepted -- bog loosestrife, earth loosestrife, swamp candles
  Machaerocereus Britton & Rose -- not accepted
  Machaerocereus eruca (Brandegee) Britton & Rose -- not accepted
  Machaerocereus gummosus (Engelm.) Britton & Rose -- not accepted
  Maihuenia patagonica (Phil) Britton & Rose -- accepted
  Mallotonia gnaphalodes (L.) Britton -- not accepted
  Malpighia shaferi Britton & P. Wilson ex Britton -- not accepted
  Malpighia thompsonii Britton & P. Wilson -- not accepted
  Malus ioensis (Alph. Wood) Britton -- accepted -- prairie crab apple, prairie crabapple
  Malus ioensis var. ioensis (Alph. Wood) Britton -- not accepted -- prairie crab apple, prairie crabapple
  Malus malus (L.) Britton -- not accepted
  Malus X soulardii (L.H. Bailey) Britton (pro sp.) -- accepted -- Soulard crab
  Malvastrum cochorifolium (Desr.) Britton ex Small -- not accepted
  Malvastrum corchorifolium (Desr.) Britton ex Small -- accepted -- false mallow
  Mamillopsis (E. Morren) F.A.C. Weber ex Britton & Rose -- not accepted
  Mamillopsis diguetii (F.A.C. Weber) Britton & Rose -- not accepted
  Mamillopsis senilis (Lodd. ex Salm-Dyck) F.A.C. Weber ex Britton & Rose -- not accepted
  Mammillaria albicans (Britton & Rose) A. Berger -- accepted
  Mammillaria albicans ssp. albicans (Britton & Rose) A. Berger -- accepted
  Mammillaria albicans ssp. fraileana (Britton & Rose) D.R. Hunt -- accepted
  Mammillaria armillata ssp. cerralboa (Britton & Rose) D.R. Hunt -- not accepted
  Mammillaria cerralboa (Britton & Rose) Orcutt -- accepted
  Mammillaria collinsii (Britton & Rose) Orcutt -- not accepted
  Mammillaria columbiana ssp. yucatanensis (Britton & Rose) D.R. Hunt -- accepted
  Mammillaria confusa (Britton & Rose) Orcutt -- not accepted
  Mammillaria evermanniana (Britton & Rose) Orcutt -- accepted
  Mammillaria fraileana (Britton & Rose) Backeb. -- not accepted
  Mammillaria grahamii ssp. sheldonii (Britton & Rose) D.R. Hunt -- accepted
  Mammillaria jaliscana (Britton & Rose) Boed. -- accepted
  Mammillaria jaliscana ssp. jaliscana (Britton & Rose) Boed. -- accepted
  Mammillaria lanata (Britton & Rose) Orcutt -- not accepted
  Mammillaria lloydii (Britton & Rose) Orcutt -- not accepted
  Mammillaria longicoma (Britton & Rose) A. Berger -- not accepted
  Mammillaria longiflora (Britton & Rose) A. Berger -- accepted
  Mammillaria longiflora ssp. longiflora (Britton & Rose) A. Berger -- accepted
  Mammillaria mercadensis (Britton & Rose) Patoni -- accepted
  Mammillaria microcarpa var. milleri (Britton & Rose) W.T. Marshall -- not accepted
  Mammillaria milleri (Britton & Rose) Boed. -- not accepted -- Biznaga de Miller
  Mammillaria milleri var. sheldonii (Britton & Rose) Neutel. -- not accepted
  Mammillaria multiformis (Britton & Rose) Backeb. -- not accepted
  Mammillaria nunezii (Britton & Rose) Orcutt -- accepted
  Mammillaria nunezii ssp. nunezii (Britton & Rose) Orcutt -- accepted
  Mammillaria occidentalis (Britton & Rose) Boed. -- not accepted
  Mammillaria peninsularis (Britton & Rose) Orcutt -- accepted
  Mammillaria pygmaea (Britton & Rose) A. Berger -- not accepted
  Mammillaria rekoi (Britton & Rose) Vaupel -- accepted
  Mammillaria rekoi ssp. rekoi (Britton & Rose) Vaupel -- accepted
  Mammillaria runyonii (Britton & Rose) Cory -- not accepted
  Mammillaria scrippsiana (Britton & Rose) Orcutt -- accepted
  Mammillaria sheldonii (Britton & Rose) Boed. -- not accepted
  Mammillaria slevinii (Britton & Rose) Boed. -- not accepted
  Mammillaria sneedi (Britton & Rose) Cory -- not accepted
  Mammillaria sneedii (Britton & Rose) Cory -- not accepted
  Mammillaria solisii (Britton & Rose) Boed. -- not accepted
  Mammillaria standleyi (Britton & Rose) Orcutt -- accepted
  Mammillaria swinglei (Britton & Rose) Boed. -- not accepted
  Mammillaria tenampensis (Britton & Rose) A. Berger -- not accepted
  Mammillaria viridiflora (Britton & Rose) Cory -- accepted -- Biznaga de flor verde, greenflower nipple cactus
  Mammillaria xanthina (Britton & Rose) Boed. -- not accepted
  Mammillaria yucatanensis (Britton & Rose) Orcutt -- not accepted
  Mariscus jamaicensis (Crantz) Britton -- not accepted
  Martiusia laurifolia (Poir.) Britton -- not accepted
  Martiusia rubiginosa (Juss. ex Pers.) Britton -- not accepted
  Matayba oppositifolia (A. Rich.) Britton -- accepted
  Matricaria grandiflora (Hook.) Britton -- not accepted
  Matucana Britton & Rose -- accepted
  Matucana haynei (Otto) Britton & Rose -- accepted
  Matucana haynei ssp. haynei (Otto) Britton & Rose -- accepted
  Maytenus elongata (Urb.) Britton -- accepted -- Puerto Rico mayten
  Maytenus ponceana Britton -- accepted -- ponce mayten
  Mediocactus Britton & Rose -- not accepted
  Mediocactus megalanthus (K. Schum. ex Vaupel) Britton & Rose -- not accepted
  Meehania Britton -- accepted
  Meehania cordata (Nutt.) Britton -- accepted -- Meehan's mint
  Megapterium fremontii (S. Watson) Britton -- not accepted
  Mehania Britton -- not accepted
  Mehania cordata (Nutt.) Britton -- not accepted
  Meibomia chapmanii (Britton) Small -- not accepted
  Meibomia procumbens (Mill.) Britton -- not accepted
  Meibomia sintenisii (Urb.) Britton -- not accepted
  Meibomia supina Britton -- not accepted
  Meibomia tweedyi (Britton) Vail -- not accepted
  Meibomia umbrosa Britton -- not accepted
  Meibomia wydleriana (Urb.) Britton -- not accepted
  Melampyrum latifolium (W.P.C. Barton) Muhl. ex Britton & A. Br. -- not accepted
  Melanthera calcicola Britton -- not accepted
  Melanthera confusa Britton -- not accepted
  Melocactus bahiensis (Britton & Rose) Luetzelb. -- accepted
  Melocactus bahiensis ssp. bahiensis (Britton & Rose) Luetzelb. -- accepted
  Melocactus broadwayi (Britton & Rose) A. Berger -- accepted -- Turk's cap
  Melocactus harlowii (Britton & Rose) Vaupel -- accepted
  Melocactus oaxacensis (Britton & Rose) Backeb. -- not accepted
  Melocactus ruestii ssp. oaxacensis (Britton & Rose) Elizondo -- not accepted
  Melocactus zehntneri (Britton & Rose) Leutzelb. -- accepted
  Menendezia biflora (Cogn.) Britton -- not accepted
  Menendezia stahlii (Cogn.) Britton -- not accepted
  Menendezia urbanii (Cogn.) Britton -- not accepted
  Mertensia alaskana Britton -- not accepted
  Mertensia paniculata var. alaskana (Britton) L.O. Williams -- accepted -- Alaska tall bluebells
  Mesadenia tuberosa (Nutt.) Britton -- not accepted
  Mesadenus lucayanus (Britton) Schltr. -- accepted -- Florida Keys ladies'-tresses, Spiranthes lucayana
  Metastelma anegadense Britton -- accepted
  Metastelma monense Britton -- accepted
  Miconia subcorymbosa Britton -- not accepted -- forest johnny berry, forest johnnyberry
  Microstylis unifolia (Michx.) Britton, Sterns & Poggenb. -- not accepted
  Mikania stevensiana Britton -- accepted -- Maricao River hempvine
  Mila Britton & Rose -- accepted
  Mila caespitosa Britton & Rose -- accepted
  Mila caespitosa ssp. caespitosa Britton & Rose -- accepted
  Mimosa hystricina (Small ex Britton & Rose) B.L. Turner -- accepted -- porcupine mimosa
  Mimosa nuttallii (DC. ex Britton & Rose) B.L. Turner -- accepted -- catclaw sensitivebriar, Nuttall's sensitive-briar
  Mimosa quadrivalvis var. hystricina (Small ex Britton & Rose) Barneby -- not accepted
  Mimosa quadrivalvis var. hystricina (Small ex Britton & Rose) Barneby -- not accepted
  Mimosa quadrivalvis var. nelsonii (Britton & Rose) Barneby -- accepted -- Nelson's mimosa
  Mimosa quadrivalvis var. nuttallii (DC. ex Britton & Rose) L.S. Beard ex Barneby -- not accepted
  Mimosa wherryana (Britton) Standl. -- not accepted
  Mimosopsis biuncifera (Benth.) Britton & Rose -- not accepted
  Mimosopsis wherryana Britton -- not accepted
  Mimusops emarginata (L.) Britton -- not accepted
  Minuartia dawsonensis (Britton) House -- accepted -- rock stitchwort
  Mirabella albicaulis (Britton & Rose) F. Ritter -- not accepted
  Mirabilis longiflora var. wrightiana (A. Gray ex Britton & Kearney) Kearney & Peebles -- not accepted -- sweet four o'clock
  Mirabilis wrightiana A. Gray ex Britton & Kearney -- not accepted
  Mitracarpus maxwelliae Britton & P. Wilson -- accepted -- Maxwell's girdlepod
  Moldavica moldavica (L.) Britton -- not accepted
  Moldavica parviflora (Nutt.) Britton -- not accepted
  Monvillea Britton & Rose -- not accepted
  Monvillea albicaulis (Britton & Rose) R. Kiesling -- not accepted
  Monvillea amazonica (K. Schum. ex Vaupel) Britton & Rose -- not accepted
  Monvillea diffusa Britton & Rose -- not accepted
  Monvillea insularis (Hemsl.) Britton & Rose -- not accepted
  Monvillea maritima Britton & Rose -- not accepted
  Monvillea phatnosperma (K. Schum.) Britton & Rose -- not accepted
  Monvillea smithiana (Britton & Rose) Backeb. -- not accepted
  Monvillea spegazzinii (F.A.C. Weber) Britton & Rose -- not accepted
  Morongia angustata (Torr. & A. Gray) Britton -- not accepted
  Morongia microphylla (Dryand.) Britton -- not accepted
  Morongia portoricensis (Urb.) Britton -- not accepted
  Morongia uncinata (Willd.) Britton -- not accepted
  Mosiera xerophytica (Britton) Salywon -- accepted -- aridland stopper
  Mouriri helleri Britton -- accepted -- mameyuelo
  Muhlenbergia racemosa (Michx.) Britton, Sterns & Poggenb. -- accepted -- green muhly, marsh muhly
  Muhlenbergia tenuiflora (Willd.) Britton, Sterns & Poggenb. -- accepted -- slender muhly
  Muhlenbergia tenuiflora ssp. tenuiflora (Willd.) Britton, Sterns & Poggenb. -- not accepted
  Muhlenbergia tenuiflora var. tenuiflora (Willd.) Britton, Sterns & Poggenb. -- not accepted -- muhlenbergie ténue variété ténue, slender muhly
  Myosotis virginica auct. non (L.) Britton, Sterns & Poggenb. -- not accepted
  Myrcia portoricensis (Britton) Cedeńo-Mald. & Breckon ex F.S. Axelrod -- accepted -- Puerto Rico lidflower
  Myriophyllum pinnatum (Walter) Britton, Sterns & Poggenb. -- accepted -- cut-leaf water-milfoil, cutleaf watermilfoil, green parrotfeather
  Myrtillocactus cochal (Orcutt) Britton & Rose -- accepted
  Myrtillocactus eichlamii Britton & Rose -- accepted
  Myrtillocactus schenckii (J.A. Purpus) Britton & Rose -- accepted
  Nama ovata (Nutt. ex Choisy) Britton -- not accepted
  Negundo aceroides ssp. interius (Britton) Á. Löve & D. Löve -- not accepted
  Negundo interius (Britton) Rydb. -- not accepted
  Neltuma velutina (Wooton) Britton & Rose -- not accepted
  Neoabbottia Britton & Rose -- not accepted
  Neoabbottia grantiana (Britton) Buxb. -- not accepted
  Neoabbottia paniculata (Lam.) Britton & Rose -- not accepted
  Neobesseya Britton & Rose -- not accepted
  Neobesseya missouriensis (Sweet) Britton & Rose -- not accepted
  Neobesseya notesteinii (Britton) Britton & Rose -- not accepted
  Neobesseya similis (Engelm. & A. Gray) Britton & Rose -- not accepted
  Neobesseya wissmannii (Hildm. ex K. Schum.) Britton & Rose -- not accepted
  Neolloydia Britton & Rose -- accepted
  Neolloydia beguinii (F.A.C. Weber ex K. Schum.) Britton & Rose -- not accepted
  Neolloydia clavata (Scheidw.) Britton & Rose -- not accepted
  Neolloydia conoidea (DC.) Britton & Rose -- accepted -- Biznaga-cónica, Chihuahuan beehive
  Neomammillaria Britton & Rose -- not accepted
  Neomammillaria multiformis Britton & Rose -- not accepted
  Neomammillaria nivosa (Link ex Pfeiff.) Britton & Rose -- not accepted
  Neomammillaria rekoi Britton & Rose -- not accepted
  Neomammillaria similis (Engelm.) Britton & Rose ex Rydb. -- not accepted
  Neopieris mariana (L.) Britton -- not accepted
  Neopieris nitida (W. Bartram ex Marshall) Britton -- not accepted
  Neoporteria Britton & Rose -- not accepted
  Neoporteria chilensis (Hildm. ex K. Schum.) Britton & Rose -- not accepted
  Neoporteria fusca (Muehlenpf.) Britton & Rose -- not accepted
  Neoporteria jussieui (Monv. ex Salm-Dyck) Britton & Rose -- not accepted
  Neoporteria nidus (Söhrens) Britton & Rose -- not accepted
  Neoporteria nigricans (Linke) Britton & Rose -- not accepted
  Neoporteria subgibbosa (Haw.) Britton & Rose -- not accepted
  Neoraimondia Britton & Rose -- accepted
  Neoraimondia macrostibas Britton & Rose -- not accepted
  Neorudolphia Britton -- accepted
  Neorudolphia volubilis (Willd.) Britton -- accepted -- bejuco de alambre
  Neovriesia macrostachya (Bello) Britton -- not accepted
  Neptunia palmeri Britton & Rose -- not accepted
  Nidema Britton & Millsp. -- accepted
  Nidema ottonis (Rchb. f.) Britton & Millsp. -- accepted -- fairy orchid
  Niopa peregrina (L.) Britton & Rose -- not accepted
  Nopalea gaumeri Britton & Rose -- not accepted
  Nopalxochia Britton & Rose -- not accepted
  Nopalxochia phyllanthoides (DC.) Britton & Rose -- not accepted
  Norta altissima (L.) Britton -- not accepted
  Norta irio (L.) Britton -- not accepted
  Nothoscordum bivalve (L.) Britton -- accepted -- crowpoison
  Nyctelea nyctelea (L.) Britton -- not accepted
  Nyctocereus (A. Berger) Britton & Rose -- not accepted
  Nyctocereus guatemalensis Britton & Rose -- not accepted
  Nyctocereus hirschtianus (K. Schum.) Britton & Rose -- not accepted
  Nyctocereus neumannii (K. Schum.) Britton & Rose -- not accepted
  Nyctocereus oaxacensis Britton & Rose -- not accepted
  Nyctocereus serpentinus (Lag. & Rodr.) Britton & Rose -- not accepted
  Nymphoides nymphaeoides (L.) Britton -- not accepted
  Ocotea coriacea (Sw.) Britton -- not accepted -- lancewood
  Oenothera grandis (Britton) Smyth -- accepted -- largeflower eveningprimrose, showy evening primrose, showy evening-primrose, showy eveningprimrose
  Oncidium bahamense Nash ex Britton & Millsp. -- not accepted
  Ophioglossum vulgatum var. alaskanum (E.G. Britton) C. Chr. -- not accepted
  Opuntia abjecta Small ex Britton & Rose -- not accepted
  Opuntia alexanderi Britton & Rose -- not accepted
  Opuntia antillana Britton & Rose -- not accepted
  Opuntia bahiensis Britton & Rose -- not accepted
  Opuntia bella Britton & Rose -- not accepted
  Opuntia boldinghii Britton & Rose -- accepted
  Opuntia boringuensis Britton & Rose -- not accepted
  Opuntia borinquensis Britton & Rose -- accepted -- olaga
  Opuntia brasiliensis ssp. bahiensis (Britton & Rose) P.J. Braun & Esteves -- not accepted
  Opuntia burrageana Britton & Rose -- not accepted
  Opuntia caribaea Britton & Rose -- not accepted
  Opuntia chaffeyi Britton & Rose -- accepted
  Opuntia covillei Britton & Rose -- not accepted
  Opuntia depauperata Britton & Rose -- not accepted
  Opuntia discolor Britton & Rose -- not accepted
  Opuntia durangensis Britton & Rose -- not accepted
  Opuntia feroacantha Britton & Rose -- not accepted
  Opuntia guatemalensis Britton & Rose -- not accepted
  Opuntia haitiensis Britton -- not accepted
  Opuntia imbricata var. viridiflora (Britton & Rose) D. Weniger -- not accepted
  Opuntia jamaicensis Britton & Harris -- not accepted
  Opuntia juniperina Britton & Rose -- not accepted
  Opuntia millspaughii Britton -- not accepted
  Opuntia nashii Britton -- not accepted
  Opuntia occidentalis var. covillei (Britton & Rose) Munz -- not accepted
  Opuntia palmadora Britton & Rose -- not accepted
  Opuntia pennellii Britton & Rose -- not accepted
  Opuntia pisciformis Small ex Britton & Rose -- not accepted
  Opuntia pittieri Britton & Rose -- accepted
  Opuntia pollardii Britton & Rose -- not accepted
  Opuntia polyacantha var. juniperina (Britton & Rose) L.D. Benson -- accepted -- Juniper pricklypear
  Opuntia salvadorensis Britton & Rose -- not accepted
  Opuntia shaferi Britton & Rose -- not accepted
  Opuntia soederstromiana Britton & Rose -- accepted
  Opuntia soehrensii Britton & Rose -- not accepted
  Opuntia taylorii Britton & Rose -- accepted
  Opuntia tracyi Britton -- not accepted
  Opuntia trichophora (Engelm. & J.M. Bigelow) Britton & Rose -- not accepted -- Nopal peludito
  Opuntia vaseyi (J.M. Coult.) Britton & Rose -- not accepted
  Opuntia wetmorei Britton & Rose -- not accepted
  Opuntia whipplei var. viridiflora (Britton & Rose) L.D. Benson -- not accepted
  Opuntia wilcoxii Britton & Rose -- accepted
  Opuntia X aequatorialis Britton & Rose (pro sp.) -- accepted
  Opuntia X cubensis Britton & Rose (pro sp.) -- accepted -- bullsuckers
  Opuntia X lucayana Britton (pro sp.) -- accepted
  Opuntia X vaseyi (J.M. Coult.) Britton & Rose (pro sp.) -- accepted
  Opuntia X viridiflora Britton & Rose (pro sp.) -- not accepted -- rattail cholla, Santa Fe cholla
  Orophaca caespitosa (Nutt.) Britton -- not accepted
  Orophaca sericea (Nutt.) Britton -- not accepted
  Oroya Britton & Rose -- accepted
  Oroya peruviana (K. Schum.) Britton & Rose -- accepted
  Oryzopsis juncea Britton, Sterns & Poggenb. -- not accepted
  Osmia borinquensis Britton -- not accepted
  Osmia corymbosa (Aubl.) Britton & P. Wilson -- not accepted
  Osmia geraniifolia (Urb.) Britton & P. Wilson -- not accepted
  Osmia sinuata (Lam.) Britton & P. Wilson -- not accepted
  Osmorhiza divaricata (Britton) Suksd. -- not accepted
  Oxypolis filiformis (Walter) Britton -- accepted -- water cowbane
  Oxypolis rigidior var. longifolia (Pursh) Britton -- not accepted
  Oxytropis arctica var. bellii (Britton ex Macoun) B. Boivin -- accepted -- Bell's arctic locoweed, Bell's locoweed
  Oxytropis bellii (Britton ex Macoun) Palib. -- not accepted
  Pachycereus (A. Berger) Britton & Rose -- accepted
  Pachycereus calvus (Engelm. ex J.M. Coult.) Britton & Rose -- not accepted
  Pachycereus chrysomallus (Lem.) Britton & Rose -- not accepted
  Pachycereus columna-trajani (Karw.) Britton & Rose -- not accepted
  Pachycereus gaumeri Britton & Rose -- accepted
  Pachycereus lepidanthus (Eichlam) Britton & Rose -- accepted
  Pachycereus marginatus (DC.) Britton & Rose -- accepted
  Pachycereus pecten-aboriginum (Engelm. ex S. Watson) Britton & Rose -- accepted
  Pachycereus pringlei (S. Watson) Britton & Rose -- accepted
  Pachycereus ruficeps (F.A.C. Weber ex Rol.-Goss.) Britton & Rose -- not accepted
  Packera antennariifolia (Britton) W.A. Weber & Á. Löve -- accepted -- shale barren ragwort, shalebarren ragwort
  Packera crawfordii (Britton) A.M. Mahoney & R.R. Kowal -- accepted
  Palicourea brevithyrsa Britton & Standl. -- not accepted
  Panicum nitidum var. pauciflorum Britton -- not accepted
  Panicum nitidum var. viride (Vasey) Britton -- not accepted
  Panicum pubescens var. barbulatum (Michx.) Britton -- not accepted
  Parakohleria sprucei (Britton ex Rusby) Wiehler -- not accepted
  Paralabatia portoricensis Britton & P. Wilson -- not accepted
  Pariti grande Britton -- not accepted
  Pariti tiliaceum (L.) A. Juss. ex Britton & Millsp. -- not accepted
  Parosela aurea (Nutt. ex Fraser) Britton -- not accepted
  Parosela dalea (L.) Britton -- not accepted
  Parosela enneandra (Nutt. ex Fraser) Britton -- not accepted
  Parosela lanata (Spreng.) Britton -- not accepted
  Parsonsia parsonsia (L.) Britton -- not accepted
  Parthenium auriculatum Britton -- not accepted
  Parthenium hispidum var. auriculatum (Britton) Rollins -- not accepted
  Parthenium integrifolium var. auriculatum (Britton) Cornelius ex Cronquist -- not accepted -- wild quinine
  Parthenocissus heptaphylla (Buckley) Britton ex Small -- accepted -- sevenleaf creeper
  Paspalum intermedium Munro ex Morong & Britton -- accepted -- intermediate paspalum
  Paurotis wrightii (Griseb. & H. Wendl.) Britton -- not accepted
  Pearcea sprucei (Britton ex Rusby) L.P. Kvist & L.E. Skog -- accepted
  Pearcea sprucei var. sprucei (Britton ex Rusby) L.P. Kvist & L.E. Skog -- accepted
  Pedilanthus grisebachii Millsp. & Britton -- not accepted
  Pedilanthus ierensis Britton -- not accepted
  Pedilanthus jamaicensis Millsp. & Britton -- not accepted
  Pedilanthus latifolius Millsp. & Britton -- not accepted
  Pedilanthus tithymaloides ssp. jamaicensis (Millsp. & Britton) Dressler -- not accepted
  Pediocactus Britton & Rose -- accepted -- hedgehog cactus
  Pediocactus simpsonii (Engelm.) Britton & Rose -- accepted -- Simpson's hedgehog cactus, snowball pediocactus
  Pediocactus simpsonii ssp. simpsonii (Engelm.) Britton & Rose -- not accepted
  Pediocactus simpsonii var. simpsonii (Engelm.) Britton & Rose -- not accepted -- Simpson hedgehog cactus, Simpson's hedgehog cactus
  Peiranisia bahamensis (Mill.) Britton & Rose -- not accepted
  Peiranisia polyphylla (Jacq.) Britton & Rose -- not accepted
  Peniocereus (A. Berger) Britton & Rose -- accepted
  Peniocereus greggii (Engelm.) Britton & Rose -- accepted -- nightblooming cereus
  Peniocereus greggii var. greggii (Engelm.) Britton & Rose -- accepted -- Gregg's nightblooming cereus
  Peniocereus guatemalensis (Britton & Rose) D.R. Hunt -- accepted
  Peniocereus johnstonii Britton & Rose -- accepted
  Peniocereus oaxacensis (Britton & Rose) D.R. Hunt -- accepted
  Peniocereus papillosus (Britton & Rose) U. Guzmán -- not accepted
  Penstemon canescens (Britton) Britton -- accepted -- eastern gray beardtongue
  Penstemon penstemon (L.) Britton -- not accepted
  Peperomia wheeleri Britton -- accepted -- Wheeler's peperomia
  Pepo ficifolia (Bouché) Britton -- not accepted
  Pepo foetidissima (Kunth) Britton -- not accepted
  Pepo moschata (Duchesne) Britton -- not accepted
  Pepo pepo (L.) Britton ex Small -- not accepted
  Pereskia colombiana Britton & Rose -- not accepted
  Pereskia conzattii Britton & Rose -- not accepted
  Pereskia cubensis Britton & Rose -- not accepted
  Pereskia humboldtii Britton & Rose -- not accepted
  Pereskia moorei Britton & Rose -- not accepted
  Pereskia zehntneri Britton & Rose -- not accepted
  Pereskiopsis Britton & Rose -- accepted
  Pereskiopsis aquosa (F.A.C. Weber) Britton & Rose -- accepted
  Pereskiopsis chapistle (F.A.C. Weber) Britton & Rose -- not accepted
  Pereskiopsis diguetii (F.A.C. Weber) Britton & Rose -- accepted
  Pereskiopsis opuntiiflora (DC.) Britton & Rose -- not accepted
  Pereskiopsis pititache (Karw. ex Pfeiff.) Britton & Rose -- not accepted
  Pereskiopsis porteri (Brandegee ex F.A.C. Weber) Britton & Rose -- accepted
  Pereskiopsis rotundifolia (DC.) Britton & Rose -- accepted
  Pereskiopsis scandens Britton & Rose -- not accepted
  Pereskiopsis spathulata (Otto ex Pfeiff.) Britton & Rose -- not accepted
  Perilla frutescens (L.) Britton -- accepted -- beefsteak mint, beefsteak plant, purple mint
  Perilla frutescens var. frutescens (L.) Britton -- accepted -- beefsteakplant
  Persea portoricensis Britton & P. Wilson -- not accepted
  Petasites gracilis Britton -- not accepted
  Petesioides pendula (Urb.) Britton -- not accepted
  Petesioides yunquensis (Urb.) Britton -- not accepted
  Petunia axillaris (Lam.) Britton, Sterns & Poggenb. -- accepted -- large white petunia
  Pfeiffera boliviana (Britton) D.R. Hunt -- accepted
  Pfeiffera crenata (Britton) P.V. Heath -- accepted
  Phaca americana (Hook.) Rydb. ex Britton & A. Br. -- not accepted
  Phaethusa helianthoides (Michx.) Britton -- not accepted
  Phaethusa occidentalis (L.) Britton -- not accepted
  Phaethusa virginica (L.) Britton -- not accepted
  Phaseolus polystachios (L.) Britton, Sterns & Poggenb. -- accepted -- slimleaf bean, thicket bean
  Phaseolus polystachios var. polystachios (L.) Britton, Sterns & Poggenb. -- accepted -- thicket bean
  Phaseolus polystachyus (L.) Britton, Sterns & Poggenb. -- not accepted
  Phellosperma Britton & Rose -- not accepted
  Phellosperma tetrancistra (Engelm.) Britton & Rose -- not accepted
  Philodendron nechodomi Britton -- not accepted
  Philodendron nechodomii Britton -- not accepted
  Philotria angustifolia (Muhl.) Britton ex Rydb. -- not accepted
  Philotria canadensis (Michx.) Britton -- not accepted
  Phlebotaenia cowellii Britton -- accepted
  Phlox amplifolia Britton -- accepted -- largeleaf phlox
  Phlox kelseyi Britton -- accepted -- Kelsey's phlox
  Phlox kelseyi ssp. kelseyi Britton -- accepted -- Kelsey's phlox
  Phoradendron randiae (Bello) Britton -- not accepted
  Phragmites vulgaris Britton, Sterns & Poggenb. -- not accepted
  Phyllanthus cuneifolius (Britton) Croizat -- accepted -- wedge leaf-flower
  Phymosia cuspidata (A. Gray) Britton -- not accepted
  Phymosia remota (Greene) Britton -- not accepted
  Physalis ambigua (A. Gray) Britton -- not accepted
  Physalodes physalodes (L.) Britton -- not accepted
  Physostegia denticulata sensu Fernald, non (Aiton) Britton -- not accepted
  Physostegia denticulata (Aiton) Britton -- not accepted
  Physostegia nuttallii (Britton) Fassett -- not accepted
  Picea canadensis (Mill.) Britton, Sterns & Poggenb. -- not accepted
  Picea mariana (Mill.) Britton, Sterns & Poggenb. -- accepted -- black spruce, bog spruce, shortleaf black spruce, swamp spruce
  Picea mariana var. mariana (Mill.) Britton, Sterns & Poggenb. -- not accepted -- black spruce
  Picradenia odorata (DC.) Britton -- not accepted
  Picradeniopsis Rydb. ex Britton -- accepted -- bahia
  Picradeniopsis oppositifolia (Nutt.) Rydb. ex Britton -- accepted -- opposite-leaf false bahia, oppositeleaf bahia, plains bahia
  Pilea margarettae Britton -- accepted -- Margarett's clearweed
  Pilea margarettiae Britton -- not accepted -- Margarett's clearweed
  Pilea yunquensis (Urb.) Britton & P. Wilson -- accepted -- mountain clearweed
  Pilosocereus bahamensis (Britton) Byles & G.D. Rowley -- not accepted
  Pilosocereus barbadensis (Britton & Rose) Byles & G.D. Rowley -- not accepted
  Pilosocereus brasiliensis (Britton & Rose) Backeb. -- accepted
  Pilosocereus brasiliensis ssp. brasiliensis (Britton & Rose) Backeb. -- accepted
  Pilosocereus brooksianus (Britton & Rose) Byles & G.D. Rowley -- not accepted
  Pilosocereus collinsii (Britton & Rose) Byles & G.D. Rowley -- accepted
  Pilosocereus gaumeri (Britton & Rose) Backeb. -- not accepted
  Pilosocereus gounellei ssp. zehntneri (Britton & Rose) Zappi -- accepted
  Pilosocereus keyensis (Britton & Rose) Byles & G.D. Rowley -- not accepted
  Pilosocereus millspaughii (Britton) Byles & G.D. Rowley -- not accepted
  Pilosocereus purpusii (Britton & Rose) Byles & G.D. Rowley -- accepted
  Pilosocereus tweedyanus (Britton & Rose) Byles & G.D. Rowley -- accepted
  Pilosocereus zehnteri (Britton & Rose) F. Ritter -- not accepted
  Piper treleaseanum Britton & P. Wilson -- not accepted
  Pisonia albida (Heimerl) Britton ex Standl. -- accepted -- corcho bobo
  Pisonia floridana Britton -- not accepted -- Rock Key devil's-claws
  Pithecellobium carbonarium (Britton) Niezgoda & Nevling -- not accepted
  Pithecellobium keyense Coker ex Britton -- accepted -- Florida Keys blackbead
  Platyopuntia discolor (Britton & Rose) F. Ritter -- not accepted
  Platyopuntia soehrensii (Britton & Rose) F. Ritter -- not accepted
  Pleurothallis crassipes sensu Britton & P. Wilson, non Lindl. -- not accepted
  Plinia sintenisii (Kiaersk.) Britton -- not accepted
  Poincianella Britton & Rose -- accepted
  Poincianella mexicana (A. Gray) Britton & Rose -- accepted -- Mexican holdback, Mexican poinciana
  Poincianella myabensis (Britton) Britton & Rose -- accepted
  Polemonium caeruleum ssp. vanbruntiae (Britton) J.F. Davidson -- not accepted
  Polemonium van-bruntiae Britton -- not accepted
  Polemonium vanbruntiae Britton -- accepted -- Jacob's ladder, polémoine de Van-Brunt, Vanbrunt's polemonium
  Polygala cowellii (Britton) S.F. Blake -- not accepted -- palo de violeta, violet tree
  Polygala penaea ssp. portoricensis (Britton) Gillis -- not accepted -- crevajosa
  Polygala portoricensis (Britton) S.F. Blake -- not accepted
  Polygala tweedyi Britton ex Wheelock -- not accepted
  Polystachya minuta (Aubl.) Britton -- not accepted
  Pomaria wootonii (Britton) B.B. Simpson -- accepted -- Wooton's holdback
  Poponax macracanthoides (Bertero ex DC.) Britton & Rose -- not accepted
  Populus cercidiphylla Britton -- not accepted
  Populus occidentalis (Rydb.) Britton ex Rydb. -- not accepted
  Populus tremuloides var. cercidiphylla (Britton) Sudw. -- not accepted
  Populus tweedyi Britton -- not accepted
  Porteranthus Britton -- not accepted -- porteranthus
  Porteranthus stipulatus (Muhl. ex Willd.) Britton -- not accepted -- Indian physic
  Porteranthus trifoliatus (L.) Britton -- not accepted -- Bowman's root
  Portulaca caulerpoides Britton & P. Wilson ex Britton -- accepted -- Puerto Rico purslane
  Praecereus euchlorus ssp. diffusus (Britton & Rose) N.P. Taylor -- accepted
  Praecereus euchlorus ssp. smithianus (Britton & Rose) N.P. Taylor -- accepted
  Praecereus maritimus (Britton & Rose) Buxb. -- not accepted
  Praecereus smithianus (Britton & Rose) Buxb. -- not accepted
  Pseudoacanthocereus brasiliensis (Britton & Rose) F. Ritter -- accepted
  Pseudognaphalium helleri (Britton) Anderb. -- accepted -- Heller's cudweed
  Pseudognaphalium helleri ssp. helleri (Britton) Anderb. -- accepted -- Heller's cudweed
  Pseudolobivia aurea (Britton & Rose) Backeb. -- not accepted
  Pseudolobivia ferox (Britton & Rose) Backeb. -- not accepted
  Pseudolobivia longispina (Britton & Rose) Backeb. ex Krainz -- not accepted
  Pseudophoenix vinifera sensu Britton & Millsp., non (Mart.) Becc. -- not accepted
  Pseudopilocereus zehntneri (Britton & Rose) P.V. Heath -- not accepted
  Pseudorhipsalis Britton & Rose -- accepted
  Pseudorhipsalis alata (Sw.) Britton & Rose -- accepted
  Pseudorhipsalis amazonica ssp. panamensis (Britton & Rose) Ralf Bauer -- accepted
  Pseudorhipsalis himantoclada (Rol.-Goss.) Britton & Rose -- accepted
  Pseudorhipsalis ramulosa ssp. jamaicensis (Britton & Harris) Doweld -- accepted
  Pseudotsuga taxifolia (Lamb.) Britton -- not accepted
  Psiguria cookiana (Britton) -- not accepted -- algodoncillo
  Psilocarya corymbifera (C. Wright) Britton -- not accepted
  Psilocarya portoricensis Britton -- not accepted
  Pterocactus fischeri Britton & Rose -- accepted
  Pterocactus hickenii Britton & Rose -- accepted
  Pterocactus pumilus Britton & Rose -- not accepted
  Pterocactus skottsbergii (Britton & Rose) Backeb. -- not accepted
  Pterocactus tuberosus (Pfeiff.) Britton & Rose -- accepted
  Ptilimnium nuttallii (DC.) Britton -- accepted -- laceflower, Nuttall's mockbishopweed
  Pulsatilla hirsutissima (Pursh) Britton -- not accepted
  Pycnanthemum flexuosum auct. non (Walter) Britton, Sterns & Poggenb. -- not accepted -- Appalachian mountainmint
  Pycnanthemum flexuosum (Walter) Britton, Sterns & Poggenb. -- accepted -- Appalachian mountainmint
  Pyrus arbutifolia var. atropurpurea (Britton) B.L. Rob. -- not accepted
  Quamasia hyacinthina (Raf.) Britton -- not accepted
  Quamoclit quamoclit (L.) Britton -- not accepted
  Quercus alexanderi Britton -- not accepted
  Quercus schneckii Britton -- not accepted
  Quercus shumardii var. schneckii (Britton) Sarg. -- not accepted -- Schneck's oak
  Quercus X rudkinii Britton (pro sp.) -- accepted -- Rudkin's oak
  Quiabentia Britton & Rose -- accepted
  Quiabentia zehntneri (Britton & Rose) Britton & Rose -- accepted
  Radicula hispida (Desv.) Britton -- not accepted
  Radicula portoricensis (Spreng.) Britton -- not accepted
  Raimannia grandis (Britton) Rose -- not accepted
  Randia portoricensis (Urb.) Britton & Standl. -- accepted -- Puerto Rico indigoberry
  Ranunculus allegheniensis Britton -- accepted -- Allegheny Mountain buttercup
  Ranunculus aquatilis var. porteri (Britton) L.D. Benson -- not accepted
  Ranunculus gelidus ssp. grayi (Britton) Hultén -- not accepted
  Ranunculus grayi Britton -- accepted -- wetslope buttercup
  Ranunculus harveyi (A. Gray) Britton -- accepted -- Harvey's buttercup
  Ranunculus harveyi var. harveyi (A. Gray) Britton -- accepted -- Harvey's buttercup
  Ranunculus macounii Britton -- accepted -- Macoun's buttercup
  Rathbunia Britton & Rose -- not accepted
  Rathbunia alamosensis (J.M. Coult.) Britton & Rose -- not accepted
  Rathbunia kerberi (K. Schum.) Britton & Rose -- not accepted
  Rathbunia sonorensis (Runge ex K. Schum.) Britton & Rose -- not accepted
  Rebutia deminuta (F.A.C. Weber) Britton & Rose -- accepted
  Rebutia deminuta ssp. deminuta (F.A.C. Weber) Britton & Rose -- accepted
  Rebutia fiebrigii (Gürke) Britton & Rose -- accepted
  Rebutia pseudominuscula (Speg.) Britton & Rose -- not accepted
  Rebutia pygmaea (R.E. Fr.) Britton & Rose -- accepted
  Rebutia steinmannii (Solms) Britton & Rose -- accepted
  Rheedia hessii Britton -- not accepted
  Rhexia aristosa Britton -- accepted -- awned meadowbeauty, awnpetal meadowbeauty
  Rhipsalidopsis Britton & Rose -- not accepted
  Rhipsalidopsis rosea (Lagerh.) Britton & Rose -- not accepted
  Rhipsalis baccifera ssp. shaferi (Britton & Rose) Barthlott & N.P. Taylor -- accepted
  Rhipsalis boliviana (Britton) Lauterb. ex Buchtien -- not accepted
  Rhipsalis burchellii Britton & Rose -- accepted
  Rhipsalis crenata (Britton) Vaupel -- not accepted
  Rhipsalis cuneata Britton & Rose -- accepted
  Rhipsalis floccosa ssp. pittieri (Britton & Rose) Barthlott & N.P. Taylor -- accepted
  Rhipsalis heteroclada Britton & Rose -- not accepted
  Rhipsalis jamaicensis Britton & Harris -- not accepted
  Rhipsalis loefgrenii Britton & Rose -- not accepted
  Rhipsalis pittieri Britton & Rose -- not accepted
  Rhipsalis russellii Britton & Rose -- accepted
  Rhipsalis shaferi Britton & Rose -- not accepted
  Rhodiola integrifolia ssp. neomexicana (Britton) H. Ohba -- accepted -- New Mexican stonecrop
  Rhodiola integrifolia ssp. neomexicana (Britton) Kartesz -- not accepted
  Rhodiola neomexicana Britton -- not accepted
  Rhodiola roanensis Britton -- not accepted
  Rhodocactus colombianus (Britton & Rose) F.M. Knuth -- not accepted
  Rhodocactus cubensis (Britton & Rose) F.M. Knuth -- not accepted
  Rhus glabra var. borealis Britton, non Rhus borealis Greene -- not accepted
  Rhus lanceolata (A. Gray) Britton -- not accepted -- prairie sumac
  Rhynchospora axillaris (Lam.) Britton -- not accepted
  Rhynchospora bahamensis Britton -- not accepted
  Rhynchospora blauneri Britton -- not accepted
  Rhynchospora borinquensis Britton -- not accepted
  Rhynchospora bruneri Britton -- not accepted
  Rhynchospora cephalantha var. microcephala (Britton) Kük. -- not accepted -- bunched beaksedge
  Rhynchospora corymbosa (L.) Britton -- accepted -- matamat
  Rhynchospora curtissii Britton -- accepted -- Curtiss' beaksedge
  Rhynchospora earlei Britton -- not accepted
  Rhynchospora edisoniana Britton ex Small -- not accepted
  Rhynchospora floridensis (Britton) H. Pfeiff. -- accepted -- Florida whitetop
  Rhynchospora globularis var. pinetorum (Britton & Small) Gale -- accepted -- globe beaksedge
  Rhynchospora glomerata var. leptocarpa Chapm. ex Britton -- not accepted
  Rhynchospora glomerata var. minor Britton -- not accepted
  Rhynchospora intermedia (Chapm.) Britton -- not accepted -- pine barren beaksedge, pinebarren beaksedge
  Rhynchospora jamaicensis Britton -- accepted -- Jamaican beaksedge
  Rhynchospora leptocarpa (Chapm. ex Britton) Small -- not accepted -- slender-fruit beaksedge
  Rhynchospora lindeniana var. bahamensis (Britton) Gale -- accepted -- Bahama beaksedge
  Rhynchospora luquillensis Britton -- not accepted
  Rhynchospora macra (C.B. Clarke ex Britton) Small -- accepted -- large beaksedge
  Rhynchospora microcephala (Britton) Britton -- accepted -- smallhead beaksedge
  Rhynchospora mixta Britton -- accepted -- mingled beaksedge
  Rhynchospora perplexa Britton -- accepted -- pineland beaksedge
  Rhynchospora perplexa var. perplexa Britton -- not accepted -- pineland beaksedge
  Rhynchospora pinetorum Britton & Small -- not accepted
  Rhynchospora planckii Britton -- not accepted
  Rhynchospora plankii Britton -- not accepted
  Rhynchospora smallii Britton -- not accepted
  Rhynchospora tracyi Britton -- accepted -- Tracy's beaksedge
  Rhytidophyllum earlei (Urb. & Britton) C.V. Morton -- not accepted
  Ribes aureum var. gracillimum (Coville & Britton) Jeps. -- accepted -- golden currant
  Ribes gracillimum Coville & Britton -- not accepted
  Ricinella ricinella (L.) Britton & P. Wilson -- not accepted
  Ridan alternifolia (L.) Britton -- not accepted
  Ritterocereus eichlamii (Britton & Rose) Backeb. -- not accepted
  Rorippa americana (A. Gray) Britton -- not accepted
  Rorippa curvisiliqua (Hook.) Bessey ex Britton -- accepted -- curvepod yellowcress
  Rorippa curvisiliqua var. curvisiliqua (Hook.) Bessey ex Britton -- not accepted -- curvepod yellowcress
  Rorippa hispida (Desv.) Britton -- not accepted
  Rorippa obtusa (Nutt.) Britton -- not accepted
  Rorippa obtusa var. alpina (S. Watson) Britton -- not accepted
  Rorippa palustris var. williamsii (Britton) Hultén -- not accepted
  Rorippa sphaerocarpa (A. Gray) Britton -- accepted -- round-fruit yellowcress, roundfruit yellowcress
  Rubus americanus (Pers.) Britton -- not accepted
  Rubus baileyanus Britton -- not accepted -- Bailey's dewberry
  Rubus invisus (L.H. Bailey) Britton -- not accepted -- upland dewberry
  Ruellia parviflora (Nees) Britton -- not accepted
  Ruellia strepens var. micrantha (Engelm. & A. Gray) Britton -- not accepted
  Sabatia dodecandra (L.) Britton, Sterns & Poggenb. -- accepted -- marsh rose gentian, marsh rosegentian
  Sabatia dodecandra var. dodecandra (L.) Britton, Sterns & Poggenb. -- accepted -- marsh rose gentian
  Sabatia simulata Britton -- not accepted
  Salix bonplandiana var. toumeyi (Britton & Shafer) C.K. Schneid. -- not accepted
  Salix toumeyi Britton & Shafer -- not accepted
  Salix vallicola (Dudley) Britton & Shafer -- not accepted
  Salvia carnosa ssp. mearnsii (Britton) Epling -- not accepted
  Salvia dorrii ssp. mearnsii (Britton) E.M. McClint. -- accepted -- Mearn sage, purple sage, Verde Valley sage
  Sarcomphalus taylorii Britton -- not accepted
  Savia bahamensis Britton -- not accepted -- Bahama maidenbush, maidenbush
  Saxifraga michauxii Britton -- not accepted -- Michaux's saxifrage
  Schefflera gleasonii (Britton & P. Wilson) Alain -- accepted -- yuquilla
  Schlegelia portoricensis (Urb.) Britton -- not accepted
  Schlumbergera gaertneri (Regel) Britton & Rose -- not accepted
  Schlumbergera russelliana (Hook.) Britton & Rose -- accepted
  Schobera angiosperma (Murray) Britton -- not accepted
  Schoenoplectus novae-angliae (Britton) M.T. Strong -- not accepted -- New England bulrush
  Schoenoplectus pungens var. longispicatus (Britton) S.G. Sm. -- accepted -- common threesquare
  Schoepfia arenaria Britton -- accepted -- arana
  Schrankia hystricina (Small ex Britton & Rose) Standl. -- not accepted
  Schrankia nuttalii var. hystricina (Small ex Britton & Rose) Isley -- not accepted
  Schrankia nuttallii (DC. ex Britton & Rose) Standl. -- not accepted
  Schrankia nuttallii var. hystricina (Small ex Britton & Rose) Isely -- not accepted
  Schrankia nuttallii var. nuttallii (DC. ex Britton & Rose) Standl. -- not accepted -- Nuttall's sensitive briar
  Sciacassia siamea (Lam.) Britton -- not accepted
  Scirpus americanus var. longispicatus Britton -- not accepted
  Scirpus atrovirens var. pallidus Britton -- not accepted
  Scirpus congdonii Britton -- accepted -- Congdon's bulrush
  Scirpus cylindricus (Torr.) Britton -- not accepted
  Scirpus nanus var. anachaetus (Torr.) Britton -- not accepted
  Scirpus novae-angliae Britton -- not accepted
  Scirpus pacificus Britton -- not accepted
  Scirpus pallidus (Britton) Fernald -- accepted -- cloaked bulrush, pale bulrush
  Scirpus pungens var. longispicatus (Britton) Roy L. Taylor & MacBryde -- not accepted
  Scirpus robustus var. novae-angliae (Britton) Beetle -- not accepted
  Scirpus X peckii Britton (pro sp.) -- accepted -- Peck's bulrush
  Scleria ciliata var. curtissii (Britton) J.W. Kessler -- not accepted
  Scleria costata (Britton) Small -- not accepted
  Scleria curtissii Britton -- accepted -- Curtiss' nutrush
  Scleria doradoensis Britton -- not accepted
  Scleria havanensis Britton -- accepted -- Havana nutrush
  Scleria pauciflora var. curtissii (Britton) Fairey -- not accepted -- Curtiss' nutrush
  Scleria reticularis var. pubescens Britton -- not accepted
  Scleria reticularis var. pumila Britton -- not accepted
  Scleria stevensiana Britton -- not accepted
  Scleria triglomerata var. minor Britton -- not accepted -- slender nutrush
  Sclerocactus Britton & Rose -- accepted -- fishhook cactus
  Sclerocactus polyancistrus (Engelm. & J.M. Bigelow) Britton & Rose -- accepted -- Mohave fishhook cactus, Mojave fishhook cactus, redspined fishhook cactus
  Sclerocactus whipplei (Engelm. & J.M. Bigelow) Britton & Rose -- accepted -- Whipple's fishhook cactus
  Sclerocactus whipplei ssp. whipplei (Engelm. & J.M. Bigelow) Britton & Rose -- not accepted
  Sclerocactus whipplei var. whipplei (Engelm. & J.M. Bigelow) Britton & Rose -- not accepted -- Whipple's fishhook cactus
  Sclerolepis uniflora (Walter) Britton, Sterns & Poggenb. -- accepted -- pink bogbutton
  Scutellaria bushii Britton -- accepted -- Bush's skullcap
  Sebesten rickseckeri (Millsp.) Britton -- not accepted
  Sebesten sebestena (L.) Britton ex Small -- not accepted
  Sedella Britton & Rose -- accepted -- mock stonecrop
  Sedella congdonii (Eastw.) Britton & Rose -- not accepted -- Congdon's mock stonecrop
  Sedella pumila (Benth.) Britton & Rose -- accepted -- Sierra mock stonecrop
  Sedum cockerellii Britton -- accepted -- Cockerell's stonecrop
  Sedum eastwoodiae (Britton) A. Berger -- not accepted -- Red Mountain stonecrop
  Sedum integrifolium ssp. neomexicanum (Britton) R.T. Clausen -- not accepted -- New Mexican stonecrop
  Sedum integrifolium var. neomexicana (Britton) R.T. Clausen -- not accepted
  Sedum laxum (Britton) A. Berger -- accepted -- roseflower stonecrop
  Sedum laxum ssp. eastwoodiae (Britton) R.T. Clausen -- not accepted
  Sedum laxum ssp. laxum (Britton) A. Berger -- not accepted -- roseflower stonecrop
  Sedum laxum var. eastwoodiae (Britton) H. Ohba -- accepted -- Red Mountain stonecrop
  Sedum laxum var. laxum (Britton) A. Berger -- accepted -- roseflower stonecrop
  Sedum leibergii Britton -- accepted -- Leiberg stonecrop
  Sedum mexicanum Britton -- accepted -- Mexican stonecrop
  Sedum rosea var. roanense (Britton) A. Berger -- not accepted
  Sedum rosea var. roanensis (Britton) A. Berger -- not accepted
  Sedum roseum var. roanense (Britton) A. Berger -- not accepted
  Sedum smallii (Britton ex Small) H.E. Ahles -- not accepted
  Sedum spathulifolium ssp. anomalum (Britton) R.T. Clausen & Uhl -- not accepted
  Sedum spathulifolium ssp. pruinosum (Britton) R.T. Clausen & Uhl -- not accepted -- broadleaf stonecrop
  Sedum spathulifolium ssp. yosemitense (Britton) R.T. Clausen -- not accepted -- Yosemite stonecrop
  Sedum spathulifolium var. pruinosum (Britton) B. Boivin -- accepted -- broadleaf stonecrop
  Sedum wootonii Britton -- not accepted
  Sedum yosemitense Britton -- not accepted
  Selenicereus (A. Berger) Britton & Rose -- accepted -- moonlight cactus
  Selenicereus boeckmanni (Otto ex Salm-Dyck) Britton & Rose -- not accepted
  Selenicereus boeckmannii (Otto ex Salm-Dyck) Britton & Rose -- not accepted
  Selenicereus brevispinus Britton & Rose -- not accepted
  Selenicereus coniflorus (Weing.) Britton & Rose -- not accepted -- coneflower moonlight cactus, Pitayita-noctirna de culebra
  Selenicereus donkelaarii (Salm-Dyck) Britton & Rose -- not accepted
  Selenicereus grandiflorus (L.) Britton & Rose -- accepted -- Pitayita-nocturna reina de la noche, queen of the night
  Selenicereus grandiflorus ssp. grandiflorus (L.) Britton & Rose -- accepted
  Selenicereus hamatus (Scheidw.) Britton & Rose -- accepted
  Selenicereus hondurensis (K. Schum. ex Weing) Britton & Rose -- not accepted
  Selenicereus inermis (Otto) Britton & Rose -- accepted
  Selenicereus kunthianus (hort. ex Salm-Dyck) Britton & Rose -- not accepted
  Selenicereus macdonaldiae (Hook.) Britton & Rose -- not accepted
  Selenicereus murrillii Britton & Rose -- accepted
  Selenicereus nelsonii (Weing.) Britton & Rose -- accepted
  Selenicereus pteranthus (Link ex A. Dietr.) Britton & Rose -- accepted -- Pitayita-nocturna flor de la noche, princess of the night
  Selenicereus spinulosus (DC.) Britton & Rose -- accepted -- nightblooming cereus, Pitayita-nocturna espinosa, vinelike moonlight cactus
  Selenicereus urbanianus (Gürke & Weing.) Britton & Rose -- not accepted
  Selenicereus vagans (Brandegee) Britton & Rose -- accepted
  Selenicereus wercklei (F.A.C. Weber) Britton & Rose -- not accepted
  Senecio alabamensis Britton ex Small -- not accepted
  Senecio antennariifolius Britton -- not accepted -- shalebarren ragwort
  Senecio balsamitae var. crawfordii (Britton) Greenm. -- not accepted
  Senecio crawfordii Britton -- not accepted
  Senecio discoideus (Hook.) Britton -- not accepted
  Senecio hallii Britton -- not accepted
  Senecio memmingeri Britton -- not accepted
  Senecio obovatus var. rotundus Britton -- not accepted
  Senecio pauperculus var. crawfordii (Britton) T.M. Barkley -- not accepted
  Senecio rotundus (Britton) Small -- not accepted
  Senecio smallii Britton -- not accepted
  Senecioides cinerea (L.) Kuntze ex Britton & P. Wilson -- not accepted
  Senegalia angustifolia (Lam.) Britton & Rose -- accepted
  Senegalia berlandieri (Benth.) Britton & Rose -- accepted -- guajillo
  Senegalia emoryana (Benth.) Britton & Rose -- not accepted
  Senegalia greggii (A. Gray) Britton & Rose -- accepted -- catclaw acacia
  Senegalia muricata (L.) Britton & Rose -- accepted -- spineless wattle
  Senegalia riparia (Kunth) Britton & Rose -- accepted
  Senegalia roemerana (Scheele) Britton & Rose -- not accepted
  Senegalia roemeriana (Scheele) Britton & Rose -- accepted -- roundflower catclaw
  Senegalia vogeliana (Steud.) Britton & Rose -- accepted -- macata bourse bastard
  Senegalia westiana (DC.) Britton & Rose -- not accepted
  Senegalia wrightii (Benth.) Britton & Rose -- not accepted
  Senna orcuttii (Britton & Rose) H.S. Irwin & Barneby -- accepted -- Orcutt's senna, Orcutt's wild sensitive plant
  Sericocarpus asteroides (L.) Britton, Sterns & Poggenb. -- accepted -- toothed whitetop aster
  Sericocarpus linifolius (L.) Britton, Sterns & Poggenb. -- accepted -- narrowleaf whitetop aster
  Sesban emerus (Aubl.) Britton & P. Wilson -- not accepted
  Sesuvium maritimum (Walter) Britton, Sterns & Poggenb. -- accepted -- annual seapurslane, slender seapurslane
  Sida humilis sensu Britton & P. Wilson -- not accepted
  Sideranthus grindelioides (Nutt.) Britton -- not accepted
  Silene menziesii ssp. williamsii (Britton) Hultén -- not accepted -- Menzies' campion
  Silene menziesii var. williamsii (Britton) B. Boivin -- not accepted
  Silene williamsii Britton -- accepted -- Williams's catchfly
  Soehrensia bruchii (Britton & Rose) Backeb. -- not accepted
  Solanum bolivianum Britton ex Rusby -- accepted
  Solanum capillipes Britton -- accepted
  Solanum hazenii Britton -- accepted
  Solanum moense Britton & Wilson -- accepted
  Solidago caroliniana (L.) Britton, Sterns & Poggenb. -- not accepted
  Solidago juncea var. ramosa Porter & Britton -- not accepted
  Solidago petiolaris var. wardii (Britton) Fernald -- not accepted
  Solidago randii (Porter) Britton -- not accepted
  Solidago wardii Britton -- not accepted
  Solisia Britton & Rose -- not accepted
  Solisia pectinata (Stein) Britton & Rose -- not accepted
  Sophia sophia (L.) Britton -- not accepted
  Sorbus arbutifolia var. atropurpurea (Britton) C.K. Schneid. -- not accepted
  Spathiger ramosus (Jacq.) Britton -- not accepted
  Spathularia michauxii (Britton) Small -- not accepted
  Spatularia michauxii (Britton) Small -- not accepted
  Sphaeralcea cuspidata (A. Gray) Britton -- not accepted
  Spiraea rubra (Hill) Britton -- not accepted
  Spiraea virginiana Britton -- accepted -- Virginia meadowsweet, Virginia spiraea
  Spiraea virginiana var. virginiana Britton -- not accepted -- Virginia meadowsweet
  Spiranthes lucayana (Britton) Cogn. -- not accepted -- green ladiestresses
  Stachys ambigua (A. Gray) Britton -- not accepted
  Stachys arenicola Britton -- not accepted
  Stachys atlantica Britton -- not accepted
  Stachys latidens Small ex Britton -- accepted -- broadtooth hedgenettle
  Stachys palustris ssp. arenicola (Britton) Gill -- not accepted -- marsh hedgenettle
  Stachys pilosa var. arenicola (Britton) G.A. Mulligan & D.B. Munro -- accepted -- hairy hedgenettle
  Stachys tenuifolia var. latidens (Small ex Britton) J.B. Nelson -- not accepted -- smooth hedgenettle
  Stanleya pinnata (Pursh) Britton -- accepted -- desert prince's-plume, golden prince's-plume
  Stanleya pinnata var. pinnata (Pursh) Britton -- accepted -- desert princesplume, golden prince's-plume, pinnate princesplume
  Stenocactus lloydii (Britton & Rose) A. Berger -- not accepted
  Stenocereus eichlamii (Britton & Rose) Buxb. -- accepted
  Stenocereus humilis (Britton & Rose) D.R. Hunt -- accepted
  Stenocereus longispinus (Britton & Rose) Buxb. -- not accepted
  Stenocereus montanus (Britton & Rose) Buxb. -- accepted
  Stenophyllus barbatus (Rottb.) Britton -- not accepted
  Stenophyllus capillaris (L.) Britton -- not accepted
  Stenophyllus carteri Britton ex Small -- not accepted
  Stenophyllus coarctatus (Elliott) Britton -- not accepted
  Stenophyllus curassavicus Britton -- not accepted
  Stenophyllus portoricensis Britton -- not accepted
  Stenophyllus stenophyllus (Elliott) Britton -- not accepted
  Stenophyllus warei (Torr.) Britton -- not accepted
  Stenostomum obtusifolium (Urb.) Britton & P. Wilson -- accepted
  Stenostomum portoricense Britton & P. Wilson -- accepted
  Stenostomum sintenisii (Urb.) Britton & P. Wilson -- accepted
  Stethoma comata (L.) Britton -- not accepted
  Stethoma verticillaris (Nees) Britton -- not accepted
  Stetsonia Britton & Rose -- accepted
  Stetsonia coryne (Salm-Dyck) Britton & Rose -- accepted
  Strombocactus Britton & Rose -- accepted
  Strombocactus disciformis (DC.) Britton & Rose -- accepted
  Strombocactus disciformis ssp. disciformis (DC.) Britton & Rose -- accepted
  Strophocactus Britton & Rose -- accepted
  Strophocactus wittii (K. Schum.) Britton & Rose -- accepted
  Strophostyles helvula var. missouriensis (S. Watson) Britton -- not accepted
  Strophostyles umbellata (Muhl. ex Willd.) Britton -- accepted -- perennial wildbean, pink fuzzybean
  Stylophyllum edule (Nutt.) Britton & Rose -- not accepted
  Stylophyllum parishii Britton -- not accepted
  Stylophyllum viscidum (S. Watson) Britton & Rose -- not accepted
  Stylosanthes biflora (L.) Britton, Sterns & Poggenb. -- accepted -- endbeak pencilflower, sidebeak pencilflower
  Subpilocereus grenadensis (Britton & Rose) Backeb. -- not accepted
  Sullivantia sullivantii (Torr. & A. Gray) Britton -- accepted -- Sullivant's coolwort
  Swartzia longiflora (Tussac) Britton & P. Wilson -- not accepted
  Symphyotrichum bahamense (Britton) G.L. Nesom -- not accepted -- Bahaman aster
  Symphyotrichum bracei (Britton ex Small) G.L. Nesom -- not accepted -- Brace's aster
  Symphyotrichum praealtum var. nebraskense (Britton) G.L. Nesom -- not accepted -- Nebraska aster
  Symphyotrichum priceae (Britton) G.L. Nesom -- accepted -- lavender oldfield aster
  Synadra hispidula (Michx.) Britton -- not accepted
  Synandra hispidula (Michx.) Britton -- not accepted -- Guyandotte beauty
  Syndesmon thalictroides (L.) Hoffmanns. ex Britton -- not accepted
  Synosma suaveolens (L.) Raf. ex Britton -- not accepted
  Tabebuia argentea (Bureau & K. Schum.) Britton -- not accepted
  Tabebuia heterophylla (DC.) Britton -- accepted -- white cedar
  Tabebuia lucida Britton -- not accepted
  Tacinga Britton & Rose -- accepted
  Tacinga funalis Britton & Rose -- accepted
  Tacinga palmadora (Britton & Rose) N.P. Taylor & Stuppy -- accepted
  Taonabo heptasepala (Krug & Urb.) Britton -- not accepted
  Taonabo luquillensis (Krug & Urb.) Britton -- not accepted
  Taonabo pachyphylla (Krug & Urb.) Britton -- not accepted
  Taonabo peduncularis (DC.) Britton -- not accepted
  Taonabo stahlii (Krug & Urb.) Britton -- not accepted
  Taonabo subsessilis Britton -- not accepted
  Tara spinosa (Molina) Britton & Rose -- accepted -- spiny holdback
  Tephrocactus alexanderi (Britton & Rose) Backeb. -- accepted
  Tephrocactus hickenii (Britton & Rose) Speg. -- not accepted
  Tephrocactus russellii (Britton & Rose) Backeb. -- not accepted
  Tepion alatum (L.) Britton -- not accepted
  Ternstroemia subsessilis (Britton) Kobuski -- accepted -- el yunque colorado
  Thalesia fasciculata (Nutt.) Britton -- not accepted
  Thalesia uniflora (L.) Britton -- not accepted
  Thalictrum coriaceum (Britton) Small -- accepted -- maid of the mist
  Thaspium trifoliatum var. aureum (L.) Britton -- accepted -- purple meadowparsnip
  Thelesperma trifidum (Poir.) Britton -- not accepted
  Thelocactus (K. Schum.) Britton & Rose -- accepted
  Thelocactus bicolor (Galeotti ex Pfeiff.) Britton & Rose -- accepted -- Biznaga-pezón bicolor, glory of Texas
  Thelocactus bicolor ssp. bicolor (Galeotti ex Pfeiff.) Britton & Rose -- accepted
  Thelocactus bicolor var. bicolor (Galeotti ex Pfeiff.) Britton & Rose -- not accepted -- glory of Texas
  Thelocactus buekii (Klein bis) Britton & Rose -- accepted
  Thelocactus hexaedrophorus (Lem.) Britton & Rose -- accepted
  Thelocactus hexaedrophorus ssp. hexaedrophorus (Lem.) Britton & Rose -- accepted
  Thelocactus hexaedrophorus ssp. lloydii (Britton & Rose) N.P. Taylor -- accepted
  Thelocactus leucacanthus (Zucc. ex Pfeiff.) Britton & Rose -- accepted
  Thelocactus leucacanthus ssp. leucacanthus (Zucc. ex Pfeiff.) Britton & Rose -- accepted
  Thelocactus rinconensis (Poselger) Britton & Rose -- accepted
  Thelocactus rinconensis ssp. rinconensis (Poselger) Britton & Rose -- accepted
  Thelocactus tulensis (Polseg.) Britton & Rose -- accepted
  Thelocactus tulensis ssp. tulensis (Polseg.) Britton & Rose -- not accepted
  Thyana portoricensis (Radlk.) Britton -- not accepted
  Thyana striata (Radlk.) Britton -- not accepted
  Thymophylla aurea (A. Gray) Greene ex Britton -- accepted -- manyawn pricklyleaf
  Thymophylla aurea var. aurea (A. Gray) Greene ex Britton -- accepted -- manyawn pricklyleaf
  Tillaeastrum aquaticum (L.) Britton -- not accepted
  Tillaeastrum drummondii (Torr. & A. Gray) Britton -- not accepted
  Tillaeastrum drummondii sensu (Torr. & A. Gray) Britton -- not accepted
  Tillaeastrum vaillantii auct. non (Willd.) Britton -- not accepted
  Tillaeastrum viride (S. Watson) Britton -- not accepted
  Tipularia unifolia Britton, Sterns & Poggenb. -- not accepted
  Tissa canadensis (Pers.) Britton -- not accepted
  Tissa marina (L.) Britton -- not accepted
  Tissa rubra (L.) Britton -- not accepted
  Tithymalus grisebachii (Millsp. & Britton) Croizat -- not accepted
  Tithymalus ierensis (Britton) Croizat -- not accepted
  Tithymalus jamaicensis (Millsp. & Britton) Croizat -- not accepted
  Tofieldia racemosa (Walter) Britton, Sterns & Poggenb. -- not accepted -- coastal false asphodel
  Tolumnia bahamensis (Nash ex Britton & Millsp.) Braem -- accepted -- variegated orchid
  Torrubia bracei Britton -- not accepted
  Torrubia discolor (Spreng.) Britton -- not accepted
  Torrubia floridana (Britton ex Small) Britton -- not accepted
  Torrubia longifolia (Heimerl) Britton -- not accepted
  Torrubia obtusata (Jacq.) Britton -- not accepted
  Toumeya Britton & Rose -- not accepted
  Toumeya papyracantha (Engelm.) Britton & Rose -- not accepted
  Toxicodendron toxicodendron (L.) Britton -- not accepted
  Tradescantia montana Shuttlw. ex Britton -- not accepted
  Tradescantia occidentalis (Britton) Smyth -- accepted -- prairie spiderwort, spiderwort
  Tradescantia occidentalis var. occidentalis (Britton) Smyth -- accepted -- prairie spiderwort
  Tradescantia subaspera var. montana (Shuttlw. ex Britton) E.S. Anderson & Woodson -- not accepted -- zigzag spiderwort
  Trema floridana Britton -- not accepted
  Trema floridanum Britton -- not accepted
  Triadenum petiolatum (Walter) Britton -- not accepted
  Tricera vahlii (Baill.) Britton -- not accepted
  Trichocereus bridgesii (Salm-Dyck) Britton & Rose -- not accepted
  Trichocereus bruchii (Britton & Rose) F. Ritter -- not accepted
  Trichocereus candicans (Gillies ex Salm-Dyck) Britton & Rose -- not accepted
  Trichocereus chiloensis (Colla) Britton & Rose -- not accepted
  Trichocereus coquimbanus (Molina) Britton & Rose -- not accepted
  Trichocereus cuzcoensis Britton & Rose -- not accepted
  Trichocereus grandis (Britton & Rose) F. Ritter -- not accepted
  Trichocereus huascha (F.A.C. Weber) Britton & Rose -- not accepted
  Trichocereus pachanoi Britton & Rose -- not accepted
  Trichocereus pasacana (F.A.C. Weber ex Rümpler) Britton & Rose -- not accepted
  Trichocereus peruvianus Britton & Rose -- not accepted
  Trichocereus schickendantzii (F.A.C. Weber) Britton & Rose -- not accepted
  Trichocereus shaferi Britton & Rose -- not accepted
  Trichocereus strigosus (Salm-Dyck) Britton & Rose -- not accepted
  Trichocereus terscheckii (J. Parm. ex Pfeiff.) Britton & Rose -- not accepted
  Trichocereus thelegonoides (Speg.) Britton & Rose -- not accepted
  Trichocereus thelegonus (F.A.C. Weber) Britton & Rose -- not accepted
  Triphora surinamensis (Lindl.) Britton -- accepted -- Hernando County noddingcaps
  Tunilla soehrensii (Britton & Rose) D.R. Hunt & Iliff -- accepted
  Typhalea fruticosa (Mill.) Britton -- not accepted
  Uniola laxa (L.) Britton, Sterns & Poggenb. -- not accepted
  Urechites lutea (L.) Britton -- not accepted
  Urechites luteus (L.) Britton -- not accepted
  Utahia Britton & Rose -- not accepted
  Utahia sileri (Engelm. ex J.M. Coult.) Britton & Rose -- not accepted
  Utricularia cleistogama (A. Gray) Britton -- not accepted
  Uva-Ursi uva-ursi (L.) Britton -- not accepted
  Uvularia nitida (Britton) Mack. -- not accepted
  Uvularia puberula var. nitida (Britton) Fernald -- not accepted
  Uvularia pudica var. nitida (Britton) Fernald -- not accepted
  Vaccaria vaccaria (L.) Britton -- not accepted
  Vaccinium nigrum (Alph. Wood) Britton -- not accepted
  Vachellia anegadensis (Britton) Seigler & Ebinger -- accepted -- blackbrush wattle
  Vachellia vernicosa (Britton & Rose) Seigler & Ebinger -- accepted -- viscid acacia
  Valerianoides strigosa (Vahl) Britton -- not accepted
  Vanilla vanilla (L.) Britton -- not accepted
  Varronia bellonis (Urb.) Britton -- accepted -- serpentine manjack
  Varronia rupicola (Urb.) Britton -- accepted -- Puerto Rico manjack
  Verbena canadensis (L.) Britton -- not accepted
  Verbena peruviana (L.) Britton -- not accepted
  Verbesina alternifolia (L.) Britton ex Kearney -- accepted -- wingstem
  Vernonia noveboracensis var. tomentosa (Elliot) Britton -- not accepted
  Viburnum dentatum var. venosum (Britton) Gleason -- accepted -- southern arrowwood
  Viburnum scabrellum var. venosum (Britton) McAtee -- not accepted
  Viburnum venosum Britton -- not accepted
  Vincetoxicum baldwynianum (Sweet) Britton -- not accepted
  Vincetoxicum carolinense (Jacq.) Britton -- not accepted
  Vincetoxicum hirsutum (Michx.) Britton -- not accepted
  Vincetoxicum obliquum (Jacq.) Britton -- not accepted
  Vincetoxicum shortii (A. Gray) Britton -- not accepted
  Vincetoxicum sintenisii (Schltr.) Britton -- not accepted
  Vincetoxicum stephanotrichum (Griseb.) Britton -- not accepted
  Vincetoxicum suberosum (L.) Britton -- not accepted
  Vincetoxicum variifolium (Schltr.) Britton -- not accepted
  Viola canadensis var. scariosa Porter ex Britton -- accepted -- Canadian white violet
  Viorna addisonii (Britton) Small -- not accepted
  Viorna pitcheri (Torr. & A. Gray) Britton -- not accepted
  Vitis heptaphylla (Buckley) Britton -- not accepted
  Washingtonia claytonii (Michx.) Britton -- not accepted
  Washingtonia divaricata Britton -- not accepted
  Washingtonia longistylis (Torr.) Britton -- not accepted
  Weberocereus Britton & Rose -- accepted
  Weberocereus biolleyi (F.A.C. Weber) Britton & Rose -- not accepted
  Weberocereus bradei (Britton & Rose) G.D. Rowley -- accepted
  Weberocereus panamensis Britton & Rose -- not accepted
  Weberocereus tunilla (F.A.C. Weber) Britton & Rose -- accepted
  Websteria submersa (C. Wright) Britton -- not accepted
  Werckleocereus Britton & Rose -- not accepted
  Werckleocereus glaber (Eichlam) Britton & Rose -- not accepted
  Werckleocereus tonduzii (F.A.C. Weber) Britton & Rose -- not accepted
  Wilcoxia Britton & Rose -- not accepted
  Wilcoxia papillosa Britton & Rose -- not accepted
  Wilcoxia poselgeri (Lem.) Britton & Rose -- not accepted
  Wilcoxia striata (Brandegee) Britton & Rose -- not accepted
  Wilcoxia viperina (F.A.C. Weber) Britton & Rose -- not accepted
  Wilmattea Britton & Rose -- not accepted
  Wilmattea minutiflora (Britton & Rose) Britton & Rose -- not accepted
  Wittiocactus panamensis (Britton & Rose) Rauschert -- not accepted
  X Sorbaronia arsenii (Britton ex L. Arsčne) G.N. Jones -- accepted -- Arsen's sorbaronia
  Xanthium commune Britton -- not accepted
  Xanthium macounii Britton -- not accepted
  Xolisma ligustrina (L.) Britton -- not accepted
  Xylophylla epiphyllantha (L.) Britton -- not accepted
  Zamia lucayana Britton -- accepted
  Zamia silicea Britton -- not accepted
  Zehntnerella Britton & Rose -- not accepted
  Zehntnerella squamulosa Britton & Rose -- not accepted
  Zizia bebbii (J.M. Coult. & Rose) Britton -- not accepted
  Ziziphus taylorii (Britton) M.C. Johnst. -- accepted -- Taylor's jujube
   

A gray bar