C
- Crystal River (2)
- Cucumber Tree (4)
- Cucurbita foetidissima (1)
- Cultivated Rice (9)
- Cumberland Mountains (2)
- Cup Plant (1)
- Cupressus goveniana (2)
- Cupressus macrocarpa (9)
- Cupressus (12)
- Curl Leaf Mountain Mahogany (1)
- Curly Mesquite (23)
- Curly Mesquite (23)
- Currituck Sound (1)
- Cuscuta (2)
- Cushion Pink (1)
- Cyathea (5)
- Cycads (17)
- Cycas revoluta (3)
- Cypress (46)
- Cypripedium acaule (1)
- Cypripedium hirsutum (1)
- Cypripedium parviflorum (1)
- Cypripedium (5)