- Campion, Bladder
- Campion, Starry
- Canada Lily
- Canada Mayflower
- Cardinal Flower
- Carolina Cranesbill
- Carrion Flower
- Catchfly, Sleepy
- Catnip
- Cat's Ear, Spotted
- Celandine
- Chickweed, Common
- Chickweed, Mouse-ear
- Chickweed, Nodding
- Chickweed, Star or Great
- Chicory
- Cinquefoil, Dwarf
- Cinquefoil, Rough
- Cinquefoil, Rough-fruited
|
|
- Common Cattail
- Common Dittany
- Common Dodder
- Common Greenbrier
- Coneflower, Tall or Green-headed
- Coneflower, Gray-headed
- Coreopsis, Greater
- Coreopsis, Tall
- Coreopsis, Whorled
- Corn Gromwell
- Corn Salad
- Corydalis, Pale
- Corydalis, Yellow
- Cowbane, Stiff
- Cow Parsnip
- Cow Wheat
- Cress, Creeping Yellow
- Cress, Early Winter
- Cress, Marsh Yellow
- Cress, Small-flowered Bitter
- Cress, Smooth Rock
- Cress, Spreading Rock
- Cress, Spring
- Crowfoot, Cursed
- Crowfoot, Hooked
- Crowfoot, Small-flowered
- Cuckooflower
|