| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| COLA6 | Corynocarpus laevigatus J.R. & G. Forst. | karaka nut | Corynocarpaceae
|
| CORYN2 | Corynocarpus J.R. & G. Forst. | corynocarpus | Corynocarpaceae
|
| COMI9 | Corypha minor Jacq. | Sabal minor | Arecaceae
|
| COPA18 | Corypha palmetto Walt. | Sabal palmetto | Arecaceae
|
| CORE8 | Corypha repens Bartr. | Serenoa repens | Arecaceae
|
| COAL9 | Coryphantha albicolumnaria (Hester) A.D. Zimmerman | Escobaria albicolumnaria | Cactaceae
|
| COAL10 | Coryphantha alversonii (Coult.) Orcutt | Escobaria alversonii | Cactaceae
|
| COAR12 | Coryphantha arizonica (Engelm.) Britt. & Rose | Escobaria vivipara var. arizonica | Cactaceae
|
| COBI5 | Coryphantha bisbeeana Orcutt | Escobaria vivipara var. bisbeeana | Cactaceae
|
| COCH5 | Coryphantha chaffeyi (Britt. & Rose) Fosberg | Escobaria dasyacantha var. chaffeyi | Cactaceae
|
| COCOE | Coryphantha cornifera (DC.) Lem. var. echinus (Engelm.) L. Benson | Coryphantha echinus | Cactaceae
|
| CODAV | Coryphantha dasyacantha (Engelm.) Orcutt var. varicolor (Tiegel) L. Benson | Escobaria tuberculosa | Cactaceae
|
| CODA | Coryphantha dasyacantha (Engelm.) Orcutt | Escobaria dasyacantha var. dasyacantha | Cactaceae
|
| CODE8 | Coryphantha deserti (Engelm.) Britt. & Rose | Escobaria vivipara var. deserti | Cactaceae
|
| CODU | Coryphantha duncanii (Hester) L. Benson | Escobaria dasyacantha var. duncanii | Cactaceae
|
| COEC | Coryphantha echinus (Engelm.) Britt. & Rose | rhinoceros cactus | Cactaceae
|
| COFR10 | Coryphantha fragrans Hester | Escobaria vivipara var. radiosa | Cactaceae
|
| COHE5 | Coryphantha hesteri Y. Wright | Escobaria hesteri | Cactaceae
|
| COMAM2 | Coryphantha macromeris (Engelm.) Lem. var. macromeris | nipple beehive cactus | Cactaceae
|
| COMAR2 | Coryphantha macromeris (Engelm.) Lem. var. runyonii (Britt. & Rose) L. Benson | Runyon's beehive cactus | Cactaceae
|
| COMA14 | Coryphantha macromeris (Engelm.) Lem. | nipple beehive cactus | Cactaceae
|
| COMI4 | Coryphantha minima Baird | Escobaria minima | Cactaceae
|
| COMIC | Coryphantha missouriensis (Sweet) Britt. & Rose var. caespitosa (Engelm.) L. Benson | Escobaria missouriensis var. similis | Cactaceae
|
| COMIM | Coryphantha missouriensis (Sweet) Britt. & Rose var. marstonii (Clover) L. Benson | Escobaria missouriensis var. marstonii | Cactaceae
|
| COMIR | Coryphantha missouriensis (Sweet) Britt. & Rose var. robustior (Engelm.) L. Benson | Escobaria missouriensis var. robustior | Cactaceae
|
| COMI5 | Coryphantha missouriensis (Sweet) Britt. & Rose | Escobaria missouriensis var. missouriensis | Cactaceae
|
| CONE2 | Coryphantha nellieae Croizat | Escobaria minima | Cactaceae
|
| CONE4 | Coryphantha neomexicana (Engelm.) Britt. & Rose | Escobaria vivipara var. neomexicana | Cactaceae
|
| CONI16 | Coryphantha nickelsiae (K. Brandeg.) Britt. & Rose | Nickels' cactus | Cactaceae
|
| COOR6 | Coryphantha organensis A.D. Zimmerman | Escobaria organensis | Cactaceae
|
| COPE2 | Coryphantha pectinata (Engelm.) Britt. & Rose | Coryphantha echinus | Cactaceae
|
| CORA8 | Coryphantha radiosa (Engelm.) Rydb. | Escobaria vivipara var. radiosa | Cactaceae
|
| CORA7 | Coryphantha ramillosa Cutak | whiskerbush | Cactaceae
|
| CORE3 | Coryphantha recurvata (Engelm.) Britt. & Rose | Santa Cruz beehive cactus | Cactaceae
|
| CORO3 | Coryphantha robbinsiorum (W.H. Earle) A.D. Zimmerman | Escobaria robbinsiorum | Cactaceae
|
| CORO2 | Coryphantha robertii Berger | Escobaria emskoetteriana | Cactaceae
|
| CORO7 | Coryphantha robustispina (Schott ex Engelm.) Britt. & Rose | Coryphantha scheeri var. robustispina | Cactaceae
|
| CORU7 | Coryphantha runyonii Britt. & Rose | Coryphantha macromeris var. runyonii | Cactaceae
|
| COSCR | Coryphantha scheeri (Muehlenpfordt) L. Benson var. robustispina (Schott ex Engelm.) L. Benson | longtubercle beehive cactus | Cactaceae
|
| COSCS | Coryphantha scheeri (Muehlenpfordt) L. Benson var. scheeri | Scheer's beehive cactus | Cactaceae
|
| COSCU | Coryphantha scheeri (Muehlenpfordt) L. Benson var. uncinata L. Benson | Scheer's beehive cactus | Cactaceae
|
| COSCV | Coryphantha scheeri (Muehlenpfordt) L. Benson var. valida (Engelm.) L. Benson | Scheer's beehive cactus | Cactaceae
|
| COSC6 | Coryphantha scheeri (Muehlenpfordt) L. Benson | Scheer's beehive cactus | Cactaceae
|
| COSI5 | Coryphantha similis (Engelm.) Britt. & Rose | Escobaria missouriensis var. similis | Cactaceae
|
| COSNL | Coryphantha sneedii (Britt. & Rose) Berger var. leei (Rose ex B�decker) L. Benson | Escobaria sneedii var. leei | Cactaceae
|
| COSN | Coryphantha sneedii (Britt. & Rose) Berger | Escobaria sneedii var. sneedii | Cactaceae
|
| COSTD | Coryphantha strobiliformis (Poselg.) Moran var. durispina (Quehl) L. Benson | Escobaria orcuttii | Cactaceae
|
| COSTO | Coryphantha strobiliformis (Poselg.) Moran var. orcuttii (B�decker) L. Benson | Escobaria orcuttii | Cactaceae
|
| COST7 | Coryphantha strobiliformis auct. non (Poselg.) Orcutt | Escobaria tuberculosa | Cactaceae
|
| COSUN | Coryphantha sulcata (Engelm.) Britt. & Rose var. nickelsiae (K. Brandeg.) L. Benson | Coryphantha nickelsiae | Cactaceae
|
| COSU7 | Coryphantha sulcata (Engelm.) Britt. & Rose | pineapple cactus | Cactaceae
|
| COVIA3 | Coryphantha vivipara (Nutt.) Britt. & Rose var. aggregata (Engelm.) W.T. Marsh. | Echinocereus coccineus var. coccineus | Cactaceae
|
| COVIA | Coryphantha vivipara (Nutt.) Britt. & Rose var. alversonii (Coult.) L. Benson | Escobaria alversonii | Cactaceae
|
| COVIA2 | Coryphantha vivipara (Nutt.) Britt. & Rose var. arizonica (Engelm.) W.T. Marsh. | Escobaria vivipara var. arizonica | Cactaceae
|
| COVIB | Coryphantha vivipara (Nutt.) Britt. & Rose var. bisbeeana (Orcutt) L. Benson | Escobaria vivipara var. bisbeeana | Cactaceae
|
| COVIB2 | Coryphantha vivipara (Nutt.) Britt. & Rose var. buoflama P.C. Fischer | Escobaria vivipara var. buoflama | Cactaceae
|
| COVID | Coryphantha vivipara (Nutt.) Britt. & Rose var. deserti (Engelm.) W.T. Marsh. | Escobaria vivipara var. deserti | Cactaceae
|
| COVIK | Coryphantha vivipara (Nutt.) Britt. & Rose var. kaibabensis P.C. Fischer | Escobaria vivipara var. kaibabensis | Cactaceae
|
| COVIN | Coryphantha vivipara (Nutt.) Britt. & Rose var. neomexicana (Engelm.) Backeberg | Escobaria vivipara var. neomexicana | Cactaceae
|
| COVIR | Coryphantha vivipara (Nutt.) Britt. & Rose var. radiosa (Engelm.) Backeberg | Escobaria vivipara var. radiosa | Cactaceae
|
| COVIR2 | Coryphantha vivipara (Nutt.) Britt. & Rose var. rosea (Clokey) L. Benson | Escobaria vivipara var. rosea | Cactaceae
|
| COVI9 | Coryphantha vivipara (Nutt.) Britt. & Rose | Escobaria vivipara var. vivipara | Cactaceae
|
| CORYP | Coryphantha (Engelm.) Lem. | beehive cactus | Cactaceae
|
| COAR14 | Coscinodon arctolimnius (Steere) Steere | coscinodon moss | Grimmiaceae
|
| COCA70 | Coscinodon calyptratus (Hook. in Drumm.) C. Jens. ex Kindb. | coscinodon moss | Grimmiaceae
|
| COCR70 | Coscinodon cribrosus (Hedw.) Spruce | coscinodon moss | Grimmiaceae
|
| CORA11 | Coscinodon raui (Aust.) Lesq. & James | Jaffueliobryum raui | Grimmiaceae
|
| COWR5 | Coscinodon wrightii Sull. in Gray | Jaffueliobryum wrightii | Grimmiaceae
|
| COSCI2 | Coscinodon Spreng. | coscinodon moss | Grimmiaceae
|
| COBI2 | Cosmos bipinnatus Cav. | garden cosmos | Asteraceae
|
| COCA21 | Cosmos caudatus Kunth | wild cosmos | Asteraceae
|
| COPA12 | Cosmos parviflorus (Jacq.) Pers. | southwestern cosmos | Asteraceae
|
| COSU5 | Cosmos sulphureus Cav. | sulphur cosmos | Asteraceae
|
| COSMO | Cosmos Cav. | cosmos | Asteraceae
|
| COCY2 | Costus cylindricus Jacq. | Costus spicatus | Costaceae
|
| COGUM | Costus guanaiensis Rusby var. macrostrobilus (K. Schum.) Maas | cana de India | Costaceae
|
| COGU | Costus guanaiensis Rusby | cana de India | Costaceae
|
| COMA13 | Costus macrostrobilus K. Schum. | Costus guanaiensis var. macrostrobilus | Costaceae
|
| COSP8 | Costus speciosus (Koenig) Sm. | canereed | Costaceae
|
| COSP4 | Costus spicatus (Jacq.) Sw. | spiked spiralflag | Costaceae
|
| COSTU | Costus L. | costus | Costaceae
|
| COAL11 | Cota altissima (L.) J. Gay | Anthemis altissima | Asteraceae
|
| COTI4 | Cota tinctoria (L.) J. Gay | Anthemis tinctoria | Asteraceae
|
| COAM11 | Cotinus americanus Nutt. | Cotinus obovatus | Anacardiaceae
|
| COCO10 | Cotinus coggygria Scop. | European smoketree | Anacardiaceae
|
| COOB2 | Cotinus obovatus Raf. | American smoketree | Anacardiaceae
|
| COTIN | Cotinus P. Mill. | smoketree | Anacardiaceae
|
| COAC2 | Cotoneaster acutifolius Turcz. | Peking cotoneaster | Rosaceae
|
| COAD | Cotoneaster adpressus Boiss. | creeping cotoneaster | Rosaceae
|
| COAP3 | Cotoneaster apiculatus Rehd. & Wilson | cranberry cotoneaster | Rosaceae
|
| CODI19 | Cotoneaster divaricatus Rehd. & Wilson | | Rosaceae
|
| COFR3 | Cotoneaster franchetii Boiss. | orange cotoneaster | Rosaceae
|
| COHO80 | Cotoneaster horizontalis Dcne. | rockspray cotoneaster | Rosaceae
|
| COHU80 | Cotoneaster hupehensis Rehd. & Wilson | Hupeh cotoneaster | Rosaceae
|
| COIN16 | Cotoneaster integerrimus Medik. | cotoneaster | Rosaceae
|
| COLA18 | Cotoneaster lacteus W.W. Smith | milkflower cotoneaster | Rosaceae
|
| COLU5 | Cotoneaster lucidus Schldl. | shiny cotoneaster | Rosaceae
|
| COMU10 | Cotoneaster multiflora Bunge | cotoneaster | Rosaceae
|
| COPA14 | Cotoneaster pannosus Franch. | silverleaf cotoneaster | Rosaceae
|
| COPY3 | Cotoneaster pyracantha (L.) Spach | Pyracantha coccinea | Rosaceae
|
| COSA4 | Cotoneaster salicifolius Franch. | cotoneaster | Rosaceae
|