| Hemizonia parryi subsp. australis D.D. Keck, 1935 |
| Hemizonia perennis (Greene) D.D. Keck, 1935 |
| Hemizonia pungens (Hook. & Arn.) Torr. & A. Gray, 1843 |
| Hemizonia pungens subsp. laevis D.D. Keck, 1935 |
| Hemizonia streetsii A. Gray, 1877 |
| Hemizonia tenella (Nutt.) A. Gray, 1874 |
| Henricksonia B.L. Turner, 1977 |
| Henricksonia mexicana B.L. Turner, 1977 |
| Hesperevax (A. Gray) A. Gray, 1868 |
| Heteropleura Sch. Bip., 1862 |
| Heteropleura fendleri (Sch. Bip.) Rydb., 1911 |
| Heterosperma Cav., 1794 |
| Heterosperma brandegeei Sherff, 1942 |
| Heterosperma coreocarpoides (Sherff) Sherff, 1942 |
| Heterosperma mexicanum (A. Gray) Lizarazu & S.E. Freire, 2018 |
| Heterosperma mexicanum var. pinnatisectum (S.F. Blake) Lizarazu & S.E. Freire, 2018 |
| Heterosperma pinnatum Cav., 1795 |
| Heterosperma xanti A. Gray, 1861 |
| Heterospermum Willd., 1803 |
| Heterotheca Cass., 1817 |