Science magazines
- Kemp's Ridley Sea Turtle
- Kendall Warm Springs Dace
- Kentucky Cave Shrimp
- Kenwood Marsh Checker-mallow
- Kern Mallow
- Kern Primrose Sphinx Moth
- Key Largo Cotton Mouse
- Key Largo Woodrat
- Key Tree-cactus
- Kincaid's Lupine
- Kio'ele
- Kiponapona
- Kirtland's Warbler
- Kneeland Prairie Penny-cress
- Knieskern's Beaked-rush
- Knowlton Cactus
- Ko'oko'olau (Bidens micrantha ssp. kalealaha)
- Ko'oko'olau (Bidens wiebkei)
- Ko'oloa'ula
- Kodachrome Bladderpod