| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| COSU13 | Collema subparvum Degel. | jelly lichen | Collemataceae
|
| COTEC3 | Collema tenax (Sw.) Ach. var. ceranoides (Borrer) Degel. | jelly lichen | Collemataceae
|
| COTEC4 | Collema tenax (Sw.) Ach. var. corallinum (A. Massal.) Degel. | coral jelly lichen | Collemataceae
|
| COTEC5 | Collema tenax (Sw.) Ach. var. crustaceum (Krempelh.) Degel. | crusty jelly lichen | Collemataceae
|
| COTES | Collema tenax (Sw.) Ach. var. substellatum (H. Magn.) Degel. | jelly lichen | Collemataceae
|
| COTE60 | Collema tenax (Sw.) Ach. | jelly lichen | Collemataceae
|
| COTE14 | Collema texanum Tuck. | Texas jelly lichen | Collemataceae
|
| COTH | Collema thamnodes Riddle | jelly lichen | Collemataceae
|
| COTU4 | Collema tuniforme (Ach.) Ach. | Collema fuscovirens | Collemataceae
|
| COUNG | Collema undulatum Laurer ex Flotow var. granulosum Degel. | undulate jelly lichen | Collemataceae
|
| COUN60 | Collema undulatum Laurer ex Flotow | undulate jelly lichen | Collemataceae
|
| COLLE2 | Collema F. H. Wigg | jelly lichen | Collemataceae
|
| COBA9 | Collemodes bachmanianum Fink | Collema bachmanianum | Collemataceae
|
| COANP | Collinsia antonina Hardham ssp. purpurea Hardham | Collinsia parryi | Scrophulariaceae
|
| COAN6 | Collinsia antonina Hardham | Collinsia parryi | Scrophulariaceae
|
| COAU7 | Collinsia austromontana (Newsom) Pennell | Collinsia heterophylla var. austromontana | Scrophulariaceae
|
| COBAB | Collinsia bartsiifolia Benth. var. bartsiifolia | white blue eyed Mary | Scrophulariaceae
|
| COBAD | Collinsia bartsiifolia Benth. var. davidsonii (Parish) Newsom | Davidson's blue eyed Mary | Scrophulariaceae
|
| COBAH | Collinsia bartsiifolia Benth. var. hirsuta (Kellogg) Pennell | white blue eyed Mary | Scrophulariaceae
|
| COBAS | Collinsia bartsiifolia Benth. var. stricta Newsom | white blue eyed Mary | Scrophulariaceae
|
| COBA | Collinsia bartsiifolia Benth. | white blue eyed Mary | Scrophulariaceae
|
| COBR | Collinsia bruceae M.E. Jones | Collinsia sparsiflora var. bruceae | Scrophulariaceae
|
| COCA3 | Collinsia callosa Parish | desertmountain blue eyed Mary | Scrophulariaceae
|
| COCH | Collinsia childii Parry ex Gray | Child's blue eyed Mary | Scrophulariaceae
|
| COCO | Collinsia concolor Greene | Chinese houses | Scrophulariaceae
|
| COCO2 | Collinsia corymbosa Herder | roundhead Chinese houses | Scrophulariaceae
|
| COFR5 | Collinsia franciscana Bioletti | Collinsia multicolor | Scrophulariaceae
|
| COGRP | Collinsia grandiflora Lindl. var. pusilla Gray | Collinsia parviflora | Scrophulariaceae
|
| COGR2 | Collinsia grandiflora Lindl. | giant blue eyed Mary | Scrophulariaceae
|
| COGR3 | Collinsia greenei Gray | Greene's blue eyed Mary | Scrophulariaceae
|
| COHEA | Collinsia heterophylla Buist ex Graham var. austromontana (Newsom) Munz | purple Chinese houses | Scrophulariaceae
|
| COHEH | Collinsia heterophylla Buist ex Graham var. heterophylla | purple Chinese houses | Scrophulariaceae
|
| COHE | Collinsia heterophylla Buist ex Graham | purple Chinese houses | Scrophulariaceae
|
| COLI | Collinsia linearis Gray | narrowleaf blue eyed Mary | Scrophulariaceae
|
| COMU | Collinsia multicolor Lindl. & Paxton | San Francisco blue eyed Mary | Scrophulariaceae
|
| COPA2 | Collinsia parryi Gray | Parry's blue eyed Mary | Scrophulariaceae
|
| COPAG | Collinsia parviflora Lindl. var. grandiflora (Lindl.) Ganders & Krause | Collinsia grandiflora | Scrophulariaceae
|
| COPA3 | Collinsia parviflora Lindl. | maiden blue eyed Mary | Scrophulariaceae
|
| CORAG | Collinsia rattanii Gray ssp. glandulosa (T.J. Howell) Pennell | sticky blue eyed Mary | Scrophulariaceae
|
| CORAR | Collinsia rattanii Gray ssp. rattanii | sticky blue eyed Mary | Scrophulariaceae
|
| CORAL4 | Collinsia rattanii Gray var. linearis (Gray) Newsom | Collinsia linearis | Scrophulariaceae
|
| CORA2 | Collinsia rattanii Gray | sticky blue eyed Mary | Scrophulariaceae
|
| COSO3 | Collinsia solitaria Kellogg | Collinsia sparsiflora var. collina | Scrophulariaceae
|
| COSPA | Collinsia sparsiflora Fisch. & C.A. Mey. var. arvensis (Greene) Jepson | spinster's blue eyed Mary | Scrophulariaceae
|
| COSPB | Collinsia sparsiflora Fisch. & C.A. Mey. var. bruceae (M.E. Jones) Newsom | spinster's blue eyed Mary | Scrophulariaceae
|
| COSPC | Collinsia sparsiflora Fisch. & C.A. Mey. var. collina (Jepson) Newsom | spinster's blue eyed Mary | Scrophulariaceae
|
| COSPS | Collinsia sparsiflora Fisch. & C.A. Mey. var. sparsiflora | spinster's blue eyed Mary | Scrophulariaceae
|
| COSP | Collinsia sparsiflora Fisch. & C.A. Mey. | spinster's blue eyed Mary | Scrophulariaceae
|
| COTE11 | Collinsia tenella (Pursh) Piper | Collinsia parviflora | Scrophulariaceae
|
| COTI | Collinsia tinctoria Hartw. ex Benth. | sticky Chinese houses | Scrophulariaceae
|
| COTOB | Collinsia torreyi Gray var. brevicarinata Newsom | Torrey's blue eyed Mary | Scrophulariaceae
|
| COTOL | Collinsia torreyi Gray var. latifolia Newsom | Torrey's blue eyed Mary | Scrophulariaceae
|
| COTOT | Collinsia torreyi Gray var. torreyi | Torrey's blue eyed Mary | Scrophulariaceae
|
| COTOW | Collinsia torreyi Gray var. wrightii (S. Wats.) I.M. Johnston | Wright's blue eyed Mary | Scrophulariaceae
|
| COTO | Collinsia torreyi Gray | Torrey's blue eyed Mary | Scrophulariaceae
|
| COVE2 | Collinsia verna Nutt. | spring blue eyed Mary | Scrophulariaceae
|
| COVI2 | Collinsia violacea Nutt. | violet blue eyed Mary | Scrophulariaceae
|
| COWR4 | Collinsia wrightii S. Wats. | Collinsia torreyi var. wrightii | Scrophulariaceae
|
| COLLI | Collinsia Nutt. | blue eyed Mary | Scrophulariaceae
|
| COCAP2 | Collinsonia canadensis L. var. punctata (Ell.) Gray | Collinsonia serotina | Lamiaceae
|
| COCA4 | Collinsonia canadensis L. | richweed | Lamiaceae
|
| COPU12 | Collinsonia punctata Ell. | Collinsonia serotina | Lamiaceae
|
| COSE11 | Collinsonia serotina Walt. | Blue Ridge horsebalm | Lamiaceae
|
| COTU2 | Collinsonia tuberosa Michx. | deepwoods horsebalm | Lamiaceae
|
| COVE3 | Collinsonia verticillata Baldw. | stoneroot | Lamiaceae
|
| COLLI2 | Collinsonia L. | horsebalm | Lamiaceae
|
| CODEC | Collomia debilis (S. Wats.) Greene var. camporum Payson | alpine collomia | Polemoniaceae
|
| CODED | Collomia debilis (S. Wats.) Greene var. debilis | alpine collomia | Polemoniaceae
|
| CODEI2 | Collomia debilis (S. Wats.) Greene var. integra Payson | Collomia debilis var. trifida | Polemoniaceae
|
| CODEI | Collomia debilis (S. Wats.) Greene var. ipomoea Payson | Collomia debilis var. debilis | Polemoniaceae
|
| CODEL | Collomia debilis (S. Wats.) Greene var. larsenii (Gray) Brand | Collomia larsenii | Polemoniaceae
|
| CODET | Collomia debilis (S. Wats.) Greene var. trifida Payson | alpine collomia | Polemoniaceae
|
| CODET2 | Collomia debilis (S. Wats.) Greene var. typica Payson | Collomia debilis var. debilis | Polemoniaceae
|
| CODE | Collomia debilis (S. Wats.) Greene | alpine collomia | Polemoniaceae
|
| CODI2 | Collomia diversifolia Greene | serpentine collomia | Polemoniaceae
|
| COGR4 | Collomia grandiflora Dougl. ex Lindl. | grand collomia | Polemoniaceae
|
| COHE2 | Collomia heterophylla Dougl. ex Hook. | variableleaf collomia | Polemoniaceae
|
| COLA8 | Collomia larsenii (Gray) Payson | talus collomia | Polemoniaceae
|
| COLI2 | Collomia linearis Nutt. | tiny trumpet | Polemoniaceae
|
| COMA3 | Collomia macrocalyx Leib. ex Brand | bristleflower collomia | Polemoniaceae
|
| COMA | Collomia mazama Coville | Mt. Mazama collomia | Polemoniaceae
|
| CORA3 | Collomia rawsoniana Greene | flaming trumpet | Polemoniaceae
|
| CORE10 | Collomia renacta E. Joyal | Barren Valley collomia | Polemoniaceae
|
| COTE | Collomia tenella Gray | diffuse collomia | Polemoniaceae
|
| COTI2 | Collomia tinctoria Kellogg | staining collomia | Polemoniaceae
|
| COTR | Collomia tracyi Mason | Tracy's collomia | Polemoniaceae
|
| COLLO | Collomia Nutt. | trumpet | Polemoniaceae
|
| COAN5 | Colocasia antiquorum Schott | Colocasia esculenta | Araceae
|
| COESA | Colocasia esculenta (L.) Schott var. antiquorum (Schott) Hubbard & Rehd. | Colocasia esculenta | Araceae
|
| COESA2 | Colocasia esculenta (L.) Schott var. aquatilis Hassk. | Colocasia esculenta | Araceae
|
| COES | Colocasia esculenta (L.) Schott | coco yam | Araceae
|
| COIN13 | Colocasia indica (Lour.) Kunth | Alocasia macrorrhizos | Araceae
|
| COLOC | Colocasia Schott | colocasia | Araceae
|
| COCI2 | Colocynthis citrullus (L.) Kuntze | Citrullus lanatus var. lanatus | Cucurbitaceae
|
| COVU | Colocynthis vulgaris Schrad. | Citrullus colocynthis | Cucurbitaceae
|
| COAN | Cologania angustifolia Kunth | longleaf cologania | Fabaceae
|
| COLE | Cologania lemmonii Gray | Lemmon's cologania | Fabaceae
|
| COLO10 | Cologania longifolia Gray | Cologania angustifolia | Fabaceae
|
| COPA4 | Cologania pallida Rose | pale cologania | Fabaceae
|
| COPU4 | Cologania pulchella Kunth | Mexican cologania | Fabaceae
|
| COLOG | Cologania Kunth | cologania | Fabaceae
|