.
| Genus | |
|---|---|
|   | Haageocereus Backeb. | 
| Haagespostoa G.D. Rowley | |
| Haastia Hook.f. | |
|   | Haemanthus L. | 
|   | Haematoxylum L. | 
| Hagenbachia Nees & Mart. | |
|   | Hakea Schrad. & J.C.Wendl. | 
|  | Halerpestes Greene | 
|   | Halesia J.Ellis ex L. | 
| Hallianthus H.E.K.Hartmann | |
| Halopeplis Bunge ex Ung.-Sternb. | |
|   | Halophytum Speg. | 
|   | Hamadryas Comm. | 
|   | Hamamelis L. | 
|   | Haplophyllum A.Juss. | 
| Harpagophytum | |
|  | Harrisia Britton | 
| Harrisinopsis G.D.Rowley | |
| Hartmanthus S.A. Hammer | |
| Hasteola Raf. | |
| Hastingsia S.Watson | |
|   | Hatiora Britton & Rose | 
| Hauya DC. | |
|   | Haymondia A.N.Egan & B.Pan bis | 
|   | Hebecarpa (Chodat) J.R.Abbott | 
| Heberdenia Banks ex A.DC. | |
|   | Hechtia Klotzsch | 
|   | Hedera L. | 
|   | Hedychium J.Koenig | 
| Hedyotis L. | |
|   | Hedysarum L. | 
|   | Helenium L. | 
|   | Helianthemum Mill. | 
|   | Helianthus L. | 
|   | Helichrysum Mill. | 
|   | Helicia Lour. | 
| Heliciopsis Sleumer | |
|   | Helicodiceros Schott ex K.Koch | 
|   | Heliconia L. | 
|   | Helicostylis Trécul | 
|   | Helicteres Pluk. ex L. | 
|   | Heliopsis Pers. | 
|   | Helleborus Tourn. ex L. | 
| Hellenia Retz. | |
|   | Helminthostachys Kaulf. | 
|   | Helonias L. | 
|   | Helosis Rich. | 
|   | Helwingia Willd. | 
|   | Hemerocallis L. | 
| Hemionitis L. | |
| Hemiphylacus S.Watson | |
|   | Henckelia Spreng. | 
|   | Hepatica Mill. | 
|   | Herbertia Sweet | 
| Hereroa (Schwantes) Dinter & Schwantes | |
|   | Herrania Goudot | 
| Herreria Ruiz & Pav. | |
| Herreriopsis H.Perrier | |
| Hertia Less. | |
| Hesperaloe Engelm. | |
|   | Hesperantha Ker Gawl. | 
|   | Hesperis L. | 
| Hesperocallis A.Gray | |
|   | Hesperocodon Eddie & Cupido | 
| Hesperoyucca (Engelm.) Trel. | |
| Heteranthemis Schott | |
|   | Heteranthera Ruiz & Pav. | 
|   | Heterocentron Hook. & Arn. | 
|   | Heteropolygonatum M.N.Tamura & Ogisu | 
|   | Heterostemma Wight & Arn. | 
|   | Heterotheca Cass. | 
|   | Hexaphylla (Klokov) P.Caputo & Del Guacchio | 
|   | Hibiscus L. | 
| Hicksbeachia F.Muell. | |
|   | Hieracium L. | 
|   | Hippeastrum Herb. | 
|   | Hippobroma G.Don | 
|   | Hippocrepis L. | 
|   | Hippolytia Poljakov | 
|   | Hippomane L. | 
|   | Hirpicium Cass. | 
|   | Hohenbergia Schult. & Schult.f. in J.J.Roemer & J.A.Schultes | 
| Hohenbergiopsis L.B.Sm. & Read | |
| Hohenmea B.R.Silva & L.F.Sousa | |
| Hollandaea F.Muell. | |
|   | Homalomena Schott | 
| Homogyne Cass. | |
|   | Hoodia Sweet ex Decne. | 
|   | Hoodiapelia G.D.Rowley | 
| Hoplocryptanthus (Mez) Leme | |
|  | Hordeum L. | 
|   | Hornstedtia Retz. | 
|   | Hosta Tratt. | 
|   | Hottarum Bogner & Nicolson | 
|   | Hottonia Boerh. ex L. | 
|   | Houstonia Gronov. | 
|   | Houttuynia Thunb. | 
|   | Hoya R.Br. | 
|   | Huernia R.Br. | 
|   | Hunnemannia Sweet | 
|   | Huperzia Bernh. | 
| Huynhia Greuter | |
|   | Hyacinthella Schur | 
|   | Hyacinthoides Heist. ex Fabr. | 
|   | Hyacinthus Tourn. ex L. | 
|   | Hyalis D.Don ex Hook. & Arn. | 
|   | Hybanthus Jacq. | 
|   | Hydnophytum Jack | 
|   | Hydnora Thunb. | 
|   | Hydrangea Gronov. ex L. | 
|   | Hydrastis J.Ellis | 
|   | Hydrocera Blume | 
|   | Hydrophyllum L. | 
| Hylandia Airy Shaw | |
| Hylocereus (A. Berger) Britton & Rose | |
|   | Hylomecon Maxim. | 
|   | Hylotelephium H.Ohba | 
| Hymenandra A.DC. | |
|   | Hymenasplenium Hayata | 
| Hymenidium Lindl. | |
|   | Hymenocallis Salisb. | 
| Hymenogyne Haw. | |
|   | Hymenolaena DC. | 
|   | Hymenoxys Cass. | 
|   | Hyoscyamus L. | 
|   | Hypecoum Tourn. ex L. | 
|   | Hypericum Tourn. ex L. | 
|  | Hypochaeris L. | 
| Hypoxis L. | |
| Hypseocharis J. Remy | |
|   | Hyptis Jacq. | 
|   | Hysterionica Willd. |