 Circaea lutetiana (Broad-Leaved Enchanter’s Nightshade) |
 Cirsium discolor (Field Thistle) |
 Cirsium muticum (Swamp Thistle) |
 Claytonia caroliniana (Carolina Spring-Beauty) |
 Claytonia virginica (Virginia Spring-Beauty) |
 Clematis viorna (Leatherflower) |
 Clematis virginiana (Virgin's-Bower) |
 Clethra alnifolia (Costal Sweet Pepperbush) |
 Clinopodium vulgare (Wild Basil) |
 Clintonia borealis (Yellow Clintonia) |
 Clintonia umbellulata (White Clintonia) |
 Coleataenia anceps (Beaked Panic Grass) |
 Coleataenia longifolia (Long-Leaved Panic Grass) |
 Collinsia verna (Blue-Eyed Mary) |
 Collinsonia canadensis (Horse-Balm) |
 Comandra umbellata (Bastard-Toadflax) |
 Comarum palustre (Marsh Cinquefoil) |
 Conoclinium coelestinum (Mistflower) |
 Conopholis americana (American Cancer-Root) |
 Conyza canadensis (Horseweed) |
 Coptis trifolia (Goldthread) |
 Corallorhiza maculata (Spotted Coralroot) |
 Corallorhiza odontorhiza (Late Coralroot) |
 Corallorhiza striata (Striped Coralroot) |
 Corallorhiza trifida (Early Coralroot) |
 Coreopsis lanceolata (Lance-Leaved Tickseed) |
 Coreopsis tinctoria (Garden Tickseed) |
 Coreopsis tripteris (Tall Tickseed) |
 Cornus alternifolia (Alternate-Leaved Dogwood) |
 Cornus canadensis (Bunchberry) |
 Cornus florida (Flowering Dogwood) |
 Cornus racemosa (Panicled Dogwood) |
 Cornus sericea (Red-Osier Dogwood) |
 Corydalis flavula (Yellow Corydalis) |
 Corylus americana (American Hazelnut) |
 Crataegus species (Hawthorn) |
 Crocanthemum canadense (Canada Rockrose) |
 Cryptotaenia canadensis (Honewort) |
 Cuphea viscosissima (Clammy Cuphea) |
 Cuscuta species (Dodder) |
 Cycloloma atriplicifolium (Winged Pigweed) |
 Cynanchum laeve (Honey-Vine) |
 Cynoglossum virginianum (Wild Comfrey) |
 Cyperus bipartitus (Shining Flat Sedge) |
 Cyperus diandrus (Umbrella Flat Sedge) |
 Cyperus lupulinus (Great Plains Flat Sedge) |
 Cyperus schweinitzii (Sand Flat Sedge) |
 Cyperus squarrosus (Bearded Flat Sedge) |
 Cyperus strigosus (Straw-Colored Flat Sedge) |
 Cypripedium acaule (Pink Lady's-Slipper) |