Index of plants by genus
| Species | Common Name | Family |
| Cacalia atriplicifolia | Pale Indian Plantain | Asteraceae |
| Cakile edentula | Sea Rocket | Brassicaceae |
| Calamagrostis canadensis | Blue Joint Grass | Poaceae |
| Calamintha arkansana | Calamint | Lamiaceae |
| Calla palustris | Wild Calla | Araceae |
| Calopogon tuberosus | Grass Pink Orchid | Orchidaceae |
| Caltha palustris | Marsh Marigold | Primulaceae |
| Calycanthus floridus | Carolina Allspice | Calycanthaceae |
| Calystegia sepium | Hedge Bindweed | Convolvulaceae |
| Camassia scilloides | Wild Hyacinth | Liliaceae |
| Campanula americana | American Bellflower | Campanulaceae |
| Campanula aparinoides | Marsh Bellflower | Campanulaceae |
| Campanula rotundifolia | Harebell | Campanulaceae |
| Campsis radicans | Trumpetvine | Bignoniaceae |
| Cardamine bulbosa | Bulbous Springcress | Brassicaceae |
| Cardamine concatenata | Cut-leaved Toothwort | Brassicaceae |
| Cardamine diphylla | Broadleaf Toothwort | Brassicaceae |
| Cardamine douglassii | Purple Springcress | Brassicaceae |
| Cardamine pensylvanica | Pennsylvania Bitter-cress | Brassicaceae |
| Cardamine pratensis | Cuckoo Flower | Brassicaceae |
| Carex appalachica | Appalachian Sedge | Cyperaceae |
| Carex arctata | Bear Sedge | Cyperaceae |
| Carex atlantica | Atlantic Star Sedge | Cyperaceae |
| Carex bebbii | Bebb's Sedge | Cyperaceae |
| Carex blanda | Common Wood Sedge | Cyperaceae |
| Carex bromoides | Brome Hummock Sedge | Cyperaceae |
| Carex brunnescens | Green Bog Sedge | Cyperaceae |
| Carex comosa | Bristly Sedge | Cyperaceae |
| Carex crawfordii | Crawford's Oval Sedge | Cyperaceae |
| Carex crinita | Fringed Sedge | Cyperaceae |
| Carex cristatella | Crested Oval Sedge | Cyperaceae |
| Carex conjuncta | Green-headed Fox Sedge | Cyperaceae |
| Carex debilis | Weak Sedge | Cyperaceae |
| Carex deweyana | Dewey's Hummock Sedge | Cyperaceae |
| Carex disperma | Two-seeded Sedge | Cyperaceae |
| Carex eburnea | Ivory Sedge | Cyperaceae |
| Carex flava | Yellow Sedge | Cyperaceae |
| Carex foenea | Bronze-headed Oval Sedge | Cyperaceae |
| Carex folliculata | Long Sedge | Cyperaceae |
| Carex gracillima | Graceful Sedge | Cyperaceae |
| Carex grayi | Common Bur Sedge | Cyperaceae |
| Carex hirsutella | Fuzzy Wuzzy Sedge | Cyperaceae |
| Carex hystericina | Porcupine Sedge | Cyperaceae |
| Carex interior | Inland Star Sedge | Cyperaceae |
| Carex intumescens | Shining Bur Sedge | Cyperaceae |
| Carex lacustris | Common Lake Sedge | Cyperaceae |
| Carex laxiculmis | Weak-stemmed Wood Sedge | Cyperaceae |
| Carex leptalea | Bristle-stalked Sedge | Cyperaceae |
| Carex leptonervia | Few-nerved Wood Sedge | Cyperaceae |
| Carex limosa | Mud Sedge | Cyperaceae |
| Carex lupulina | Common Hop Sedge | Cyperaceae |
| Carex lurida | Sallow Sedge, Bottlebrush Sedge | Cyperaceae |
| Carex pallescens | Pale Green Sedge | Cyperaceae |
| Carex pedunculata | Long-stalked Sedge | Cyperaceae |
| Carex pellita | Woolly Sedge | Cyperaceae |
| Carex pensylvanica | Common Oak Sedge | Cyperaceae |
| Carex plantaginea | Plantain-leaved Sedge | Cyperaceae |
| Carex platyphylla | Broad-leaved Sedge | Cyperaceae |
| Carex prasina | Drooping Sedge | Cyperaceae |
| Carex projecta | Necklace Sedge | Cyperaceae |
| Carex radiata | Straight-styled Wood Sedge | Cyperaceae |
| Carex rosea | Curly-styled Wood Sedge | Cyperaceae |
| Carex scabrata | Rough Sedge | Cyperaceae |
| Carex scoparia | Lance-fruited Oval Sedge | Cyperaceae |
| Carex seorsa | Swamp Star Sedge | Cyperaceae |
| Carex squarrosa | Squarrose Sedge | Cyperaceae |
| Carex stipata | Common Fox Sedge | Cyperaceae |
| Carex stricta | Tussock Sedge | Cyperaceae |
| Carex swanii | Downy Green Sedge | Cyperaceae |
| Carex tenera | Quill Sedge | Cyperaceae |
| Carex tribuloides | Awl-fruited Oval Sedge | Cyperaceae |
| Carex trisperma | Three-seeded Bog Sedge | Cyperaceae |
| Carex vulpinoidea | Brown Fox Sedge | Cyperaceae |
| Carpinus caroliniana | American Hornbeam | Betulaceae |
| Carya cordiformis | Yellowbud Hickory | Juglandaceae |
| Carya glabra | Pignut Hickory | Juglandaceae |
| Carya ovata | Shagbark Hickory | Juglandaceae |
| Castanea dentata | American Chestnut | Fagaceae |
| Castilleja coccinea | Indian Paintbrush | Scrophulariaceae |
| Castilleja sessiflora | Downy Indian Paintbrush | Scrophulariaceae |
| Catalpa speciosa | Catalpa | Bignoniaceae |
| Caulophyllum thalictroides | Blue Cohosh | Berberidaceae |
| Ceanothus americanus | New Jersey Tea | Rhamnaceae |
| Ceanothus herbaceus | Inland New Jersey Tea | Rhamnaceae |
| Celastrus scandens | American Bittersweet | Celastraceae |
| Celtis occidentalis | Hackberry | Ulmaceae |
| Cephalanthus occidentalis | Buttonbush | Rubiaceae |
| Ceratodon purpureus | Purple Ceratodon | Ditrichaceae |
| Cercis canadensis | Redbud | Caesalpiniaceae |
| Chamaedaphne calyculata | Leatherleaf | Ericaceae |
| Chara spp. | Muskgrass | Characeae |
| Chelone glabra | White Turtlehead | Scrophulariaceae |
| Chelone obliqua | Red Turtlehead | Scrophulariaceae |
| Chenopodium berlandieri | Pitseed Goosefoot, Lambsquarters | Chenopodiaceae |
| Chimaphila maculata | Spotted Wintergreen | Pyrolaceae |
| Chimaphila umbellata | Pipsissewa | Pyrolaceae |
| Cicuta bulbifera | Bulbet-bearing Water Hemlock | Apiaceae |
| Cicuta maculata | Spotted Water Hemlock | Apiaceae |
| Cimicifuga racemosa | Bugbane | Ranunculaceae |
| Cinna latifolia | Drooping Woodreed | Poaceae |
| Circaea alpina | Alpine Enchanter's Nightshade | Onagraceae |
| Circaea lutetiana | Broadleaf Enchanter's Nightshade | Onagraceae |
| Cirsium muticum | Fen Thistle | Asteraceae |
| Cirsium pitcheri | Dune Thistle | Asteraceae |
| Cladonia cristatella | British Soldier Lichen | |
| Cladrastis kentukea | Yellowwood | Fabaceae |
| Claytonia caroliniana | Carolina Spring Beauty | Portulacaceae |
| Claytonia virginica | Spring Beauty | Portulacaceae |
| Clematis occidentalis | Western Blue Virginsbower | Ranunculaceae |
| Clematis virginiana | Virginsbower | Ranunculaceae |
| Clethra alnifolia | Summersweet | Clethraceae |
| Climacium dendroides | Tree Moss | Climaciaceae |
| Clintonia borealis | Bluebead Lily | Liliaceae |
| Collinsonia canadensis | Horsebalm | Lamiaceae |
| Comandra umbellata | Bastard Toadflax | Santalaceae |
| Comptonia peregrina | Sweet Fern | Myricaceae |
| Conioselinum chinense | Hemlock-parsley | Apiaceae |
| Conocephalum conicum | Scented Liverwort | Conocephalaceae |
| Conopholis americana | Squaw Root | Orobanchaceae |
| Conyza canadensis | Canadian Horseweed | Asteraceae |
| Coptis trifolia | Goldthread | Ranunculaceae |
| Corallorhiza trifida | Early Coralroot | Orchidaceae |
| Coreopsis lanceolata | Lance-leaved Coreopsis | Asteraceae |
| Coreopsis palmata | Prairie Coreopsis | Asteraceae |
| Coreopsis tripteris | Tall Coreopsis | Asteraceae |
| Cornus canadensis | Bunchberry | Cornaceae |
| Cornus alternifolia | Pagoda Dogwood | Cornaceae |
| Cornus florida | Flowering Dogwood | Cornaceae |
| Cornus obliqua | Silky Dogwood | Cornaceae |
| Cornus racemosa | Gray Dogwood | Cornaceae |
| Cornus rugosa | Roundleaf Dogwood | Cornaceae |
| Cornus sericea | Red Osier Dogwood | Cornaceae |
| Corylus americana | American Filbert | Betulaceae |
| Corylus cornuta | Beaked Hazelnut | Betulaceae |
| Coryphantha vivipara | Spinystar | Cactaceae |
| Crataegus crus-galli | Cockspur Hawthorn | Rosaceae |
| Crataegus mollis | Downy Hawthorn | Rosaceae |
| Crataegus pruinosa | Frosted Hawthorn | Rosaceae |
| Cryptotaenia canadensis | Canadian Honewort | Apiaceae |
| Cuscuta cephalanthi | Buttonbush Dodder | Convolvulaceae |
| Cuscuta gronovii | Common Dodder | Convolvulaceae |
| Cycloloma atriplicifolium | Winged Pigweed | Chenopodiaceae |
| Cyperus bipartitus | Brook Nut Sedge | Cyperaceae |
| Cyperus filiculmis | Slender Sand Sedge | Cyperaceae |
| Cyperus lupulinus | Sand Sedge | Cyperaceae |
| Cyperus strigosus | Long-scaled Nut Sedge | Cyperaceae |
| Cypripedium acaule | Pink Lady's Slipper | Orchidaceae |
| Cypripedium candidum | White Lady's Slipper | Orchidaceae |
| Cypripedium parviflorum | Yellow Lady's Slipper | Orchidaceae |
| Cystopteris bulbifera | Bulblet Fern | Dryopteridaceae |
© 2004-2009 Michael Hough