| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| COTON | Cotoneaster Medik. | cotoneaster | Rosaceae
|
| COPA13 | Cottea pappophoroides Kunth | cotta grass | Poaceae
|
| COTTE | Cottea Kunth | cotta grass | Poaceae
|
| COAU3 | Cotula australis (Sieber) Hook. f. | Australian waterbuttons | Asteraceae
|
| COCO7 | Cotula coronopifolia L. | common brassbuttons | Asteraceae
|
| COME15 | Cotula mexicana (DC.) Cabrera | Mexican brassbuttons | Asteraceae
|
| COVE7 | Cotula verbesina L. | Adenostemma verbesina | Asteraceae
|
| COVI15 | Cotula viscosa L. | Egletes viscosa | Asteraceae
|
| COTUL | Cotula L. | waterbuttons | Asteraceae
|
| COBA15 | Cotyledon barbeyi Schweinf. ex Baker | | Crassulaceae
|
| COGL12 | Cotyledon glandulifera Henderson | Sedum moranii | Crassulaceae
|
| COORO | Cotyledon orbiculata L. var. oblongata (Haw.) DC. | pig's ear | Crassulaceae
|
| COOR2 | Cotyledon orbiculata L. | pig's ear | Crassulaceae
|
| COOR9 | Cotyledon oregonensis S. Wats. | Sedum oregonense | Crassulaceae
|
| COPI4 | Cotyledon pinnata Lam. | Kalanchoe pinnata | Crassulaceae
|
| CORU9 | Cotyledon rusbyi Greene | Graptopetalum rusbyi | Crassulaceae
|
| COST14 | Cotyledon strictiflora (Gray) Baker | Echeveria strictiflora | Crassulaceae
|
| COTYL | Cotyledon L. | pig's ear | Crassulaceae
|
| COOD5 | Coumarouna odora Aublet | Dipteryx odorata | Fabaceae
|
| COOD6 | Coumarouna odorata Aublet | Dipteryx odorata | Fabaceae
|
| COGU3 | Couroupita guianensis Aubl. | cannonball tree | Lecythidaceae
|
| COURO | Couroupita Aubl. | cannonball tree | Lecythidaceae
|
| COAX | Coursetia axillaris Coult. & Rose | Texas babybonnets | Fabaceae
|
| COCAC6 | Coursetia caribaea (Jacq.) Lavin var. caribaea | anil falso | Fabaceae
|
| COCAS2 | Coursetia caribaea (Jacq.) Lavin var. sericea (Gray) Lavin | anil falso | Fabaceae
|
| COCA31 | Coursetia caribaea (Jacq.) Lavin | anil falso | Fabaceae
|
| COGL7 | Coursetia glabella (Gray) Lavin | smooth babybonnets | Fabaceae
|
| COGL8 | Coursetia glandulosa Gray | rosary babybonnets | Fabaceae
|
| COMI3 | Coursetia microphylla Gray | Coursetia glandulosa | Fabaceae
|
| COURS | Coursetia DC. | babybonnets | Fabaceae
|
| COTR10 | Covillea tridentata (Sess� & Moc. ex DC.) Vail | Larrea tridentata var. tridentata | Zygophyllaceae
|
| COAL8 | Cowania alba Goodding | Purshia stansburiana | Rosaceae
|
| COER4 | Cowania ericifolia Torr. ex Gray | Purshia ericifolia | Rosaceae
|
| COMED | Cowania mexicana D. Don var. dubia Brandeg. | Purshia mexicana | Rosaceae
|
| COMES | Cowania mexicana D. Don var. stansburiana (Torr.) Jepson | Purshia stansburiana | Rosaceae
|
| COME5 | Cowania mexicana D. Don | Purshia mexicana | Rosaceae
|
| COST10 | Cowania stansburiana Torr. | Purshia stansburiana | Rosaceae
|
| COSU6 | Cowania subintegra Kearney | Purshia subintegra | Rosaceae
|
| CRAM8 | Cracca ambigua (M.A. Curtis) Kuntze | Tephrosia florida | Fabaceae
|
| CRAN7 | Cracca angustifolia (Featherman) Pennell | Tephrosia onobrychoides | Fabaceae
|
| CRAN13 | Cracca angustissima (Shuttlw. ex Chapman) Kuntze | Tephrosia angustissima var. angustissima | Fabaceae
|
| CRCA10 | Cracca candida (DC.) Kunth | Tephrosia candida | Fabaceae
|
| CRCA11 | Cracca caribaea (Jacq.) Benth. | Coursetia caribaea var. caribaea | Fabaceae
|
| CRCA12 | Cracca carpenteri Rydb. | Tephrosia chrysophylla | Fabaceae
|
| CRCA18 | Cracca cathartica (Sess� & Moc.) Britt. & Millsp. | Tephrosia senna | Fabaceae
|
| CRCH4 | Cracca chapmanii (Vail) Small | Tephrosia chrysophylla | Fabaceae
|
| CRCH5 | Cracca chrysophylla (Pursh) Kuntze | Tephrosia chrysophylla | Fabaceae
|
| CRCI5 | Cracca cinerea (L.) Morong | Tephrosia cinerea | Fabaceae
|
| CRCO25 | Cracca corallicola Small | Tephrosia angustissima var. corallicola | Fabaceae
|
| CRCU3 | Cracca curtissii Small ex Rydb. | Tephrosia angustissima var. curtissii | Fabaceae
|
| CREDG | Cracca edwardsii Gray var. glabella Gray | Coursetia glabella | Fabaceae
|
| CREDS | Cracca edwardsii Gray var. sericea Gray | Coursetia caribaea var. sericea | Fabaceae
|
| CRED | Cracca edwardsii Gray p.p. | Coursetia caribaea var. caribaea | Fabaceae
|
| CRFL8 | Cracca flexuosa (Vail) Heller | Tephrosia spicata | Fabaceae
|
| CRFL15 | Cracca floridana Vail | Tephrosia floridana | Fabaceae
|
| CRGL11 | Cracca glabella (Gray) Lavin | Coursetia glabella | Fabaceae
|
| CRGR5 | Cracca gracillima (B.L. Robins.) Heller | Tephrosia florida | Fabaceae
|
| CRHI5 | Cracca hispidula (Michx.) Kuntze | Tephrosia hispidula | Fabaceae
|
| CRIN12 | Cracca intermedia Small | Tephrosia floridana | Fabaceae
|
| CRLA6 | Cracca latidens Small | Tephrosia virginiana | Fabaceae
|
| CRLE9 | Cracca leiocarpa (Gray) Kuntze | Tephrosia leiocarpa | Fabaceae
|
| CRMO8 | Cracca mohrii Rydb. | Tephrosia mohrii | Fabaceae
|
| CRON | Cracca onobrychoides (Nutt.) Kuntze | Tephrosia onobrychoides | Fabaceae
|
| CRPO12 | Cracca potosina (Brandeg.) Standl. | Tephrosia potosina | Fabaceae
|
| CRPU12 | Cracca purpurea L. | Tephrosia purpurea | Fabaceae
|
| CRRU6 | Cracca rugelii (Shuttlw. ex B.L. Robins.) Heller | Tephrosia rugelii | Fabaceae
|
| CRSE8 | Cracca sericea (Gray) Gray | Coursetia caribaea var. sericea | Fabaceae
|
| CRSM | Cracca smallii Vail | Tephrosia floridana | Fabaceae
|
| CRSP7 | Cracca spicata (Walt.) Kuntze | Tephrosia spicata | Fabaceae
|
| CRTE7 | Cracca texana Rydb. | Tephrosia onobrychoides | Fabaceae
|
| CRTH5 | Cracca thurberi Rydb. | Tephrosia thurberi | Fabaceae
|
| CRVI7 | Cracca virginiana L. | Tephrosia virginiana | Fabaceae
|
| CRAB5 | Crambe abyssinica Hochst. ex R. E. Fries | crambe | Brassicaceae
|
| CRHI6 | Crambe hispanica L. | hispanic crambe | Brassicaceae
|
| CRMA | Crambe maritima L. | sea kale | Brassicaceae
|
| CRAMB | Crambe L. | crambe | Brassicaceae
|
| CRMU3 | Cranichis muscosa Sw. | cypress-knee helmet orchid | Orchidaceae
|
| CROL | Cranichis oligantha Sw. | Prescotia oligantha | Orchidaceae
|
| CRRI4 | Cranichis ricartii Ackerman | Puerto Rico helmet orchid | Orchidaceae
|
| CRST8 | Cranichis stachyodes Sw. | Prescotia stachyodes | Orchidaceae
|
| CRTE6 | Cranichis tenuis Reichenb. f. | narrow helmet orchid | Orchidaceae
|
| CRANI | Cranichis Sw. | helmet orchid | Orchidaceae
|
| CRAN8 | Craniolaria annua L. | escorzonera | Pedaliaceae
|
| CRANI2 | Craniolaria L. | craniolaria | Pedaliaceae
|
| CRAM9 | Crantzia ambigua (Urban) Britt. | Columnea ambigua | Gesneriaceae
|
| CRMU9 | Craspedophyllum mucronifolium auct. Amer. | Groutiella tumidula | Orthotrichaceae
|
| CREL6 | Crassina elegans (Jacq.) Kuntze | Zinnia violacea | Asteraceae
|
| CRGR12 | Crassina grandiflora (Nutt.) Kuntze | Zinnia grandiflora | Asteraceae
|
| CRMU7 | Crassina multiflora (L.) Kuntze | Zinnia peruviana | Asteraceae
|
| CRCR9 | Crassocephalum crepidioides (Benth.) S. Moore | redflower ragleaf | Asteraceae
|
| CRVI15 | Crassocephalum vitellinum (Benth.) S. Moore | | Asteraceae
|
| CRASS2 | Crassocephalum Moench | ragleaf | Asteraceae
|
| CRAQ | Crassula aquatica (L.) Schoenl. | water pygmyweed | Crassulaceae
|
| CRCOC | Crassula connata (Ruiz & Pav�n) Berger var. connata | sand pygmyweed | Crassulaceae
|
| CRCOE | Crassula connata (Ruiz & Pav�n) Berger var. erectoides Bywater & Wickens | sand pygmyweed | Crassulaceae
|
| CRCOE2 | Crassula connata (Ruiz & Pav�n) Berger var. eremica (Jepson) Bywater & Wickens | sand pygmyweed | Crassulaceae
|
| CRCOS | Crassula connata (Ruiz & Pav�n) Berger var. subsimplex (S. Wats.) Bywater & Wickens | sand pygmyweed | Crassulaceae
|
| CRCO34 | Crassula connata (Ruiz & Pav�n) Berger | sand pygmyweed | Crassulaceae
|
| CRDR | Crassula drummondii (Torr. & Gray) Fedde | small-leaf pygmyweed | Crassulaceae
|
| CRDR2 | Crassula drummondii auct. non sensu (Torr. & Gray) Fedde p.p. | Crassula longipes | Crassulaceae
|
| CRER2 | Crassula erecta (Hook. & Arn.) Berger | Crassula connata var. connata | Crassulaceae
|