Science magazines
- Hine's Emerald Dragonfly
- Hoffman's Rock-cress
- Hoffmann's Slender-flowered Gilia
- Holei
- Holy Ghost Ipomopsis
- Honohono
- Hoover's Spurge
- Hoover's Woolly-star
- Horned Guan
- Houghton's Goldenrod
- Houston Toad
- Howell's Spectacular Thelypody
- Howell's Spineflower
- Huachuca Water-umbel
- Hualapai Mexican Vole
- Humpback Chub
- Hungerford's Crawling Water Beetle
- Hutton Spring Tui Chub
- Idaho Springsnail
- Ilex sintenisii