Science magazines
- California Red-legged Frog
- California Sea-blite
- California Taraxacum
- Calistoga Allocarya
- Callippe Silverspot Butterfly
- Calyptranthes Thomasiana
- Canada Lynx
- Canby's Dropwort
- Canelo Hills Ladies'-tresses
- Capa Rosa
- Cape Fear Shiner
- Cape Sable Seaside Sparrow
- Caribbean Monk Seal
- Carolina Heelsplitter
- Carolina Northern Flying Squirrel
- Carter's Mustard
- Carter's Panicgrass
- Catalina Island Mountain-mahogany
- Catesbaea Melanocarpa
- Catspaw