Index of plants by genus
| Species | Common Name | Family |
| Halesia tetraptera | Carolina Silverbell | Styracaceae |
| Hamamelis virginiana | American Witchhazel | Hamamelidaceae |
| Helenium autumnale | Sneezeweed | Asteraceae |
| Helianthemum canadense | Longbranch Frostweed | Cistaceae |
| Helianthus grosseserratus | Sawtooth Sunflower | Asteraceae |
| Helianthus mollis | Downy Sunflower | Asteraceae |
| Helianthus occidentalis | Western Sunflower | Asteraceae |
| Helianthus strumosus | Pale-leaved Sunflower | Asteraceae |
| Heliopsis helianthoides | False Sunflower | Asteraceae |
| Hepatica acutiloba | Sharp-lobed Hepatica | Ranunculaceae |
| Hepatica americana | Round-lobed Hepatica | Ranunculaceae |
| Heracleum maximum | Cow Parsnip | Apiaceae |
| Heuchera richardsonii | Prairie Alumroot | Saxifragaceae |
| Hudsonia tomentosa | False Heather | Cistaceae |
| Hydrangea arborescens | ||
| Hydrangia quercifolia | ||
| Hydrophyllum virginianum | Virginia Waterleaf | Hydrophyllaceae |
| Hypericum kalmianum | Kalm's St. John's Wort | Hypericaceae |
| Hypoxis hirsuta | Yellow Star Grass | Amaryllidaceae |
| Hystrix patula | Bottlebrush Grass | Poaceae |
© 2004 Michael Hough