| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| HESC10 | Hemizonia scabrella E. Drew | Calycadenia truncata ssp. scabrella | Asteraceae
|
| HESP7 | Hemizonia spicata Greene | Calycadenia spicata | Asteraceae
|
| HETE17 | Hemizonia tenella (Nutt.) Gray | Osmadenia tenella | Asteraceae
|
| HETR | Hemizonia tracyi (Babcock & Hall) Keck | Hemizonia congesta ssp. tracyi | Asteraceae
|
| HETR7 | Hemizonia truncata (DC.) Gray | Calycadenia truncata ssp. truncata | Asteraceae
|
| HEMIZ | Hemizonia DC. | tarweed | Asteraceae
|
| HEGE3 | Henicodium geniculatum (Mitt.) Buck | henicodium moss | Pterobryaceae
|
| HENIC2 | Henicodium (C. M�ll.) Kindb. | henicodium moss | Pterobryaceae
|
| HEFA5 | Henriettea fascicularis (Sw.) G. Maza | camasey peludo | Melastomataceae
|
| HEMA11 | Henriettea macfadyenii (Triana) Alain | MacFadyen's camasey | Melastomataceae
|
| HEME5 | Henriettea membranifolia (Cogn.) Alain | thinleaf camasey | Melastomataceae
|
| HESQ | Henriettea squamulosum (Cogn.) Judd | jusillo | Melastomataceae
|
| HETR5 | Henriettea triflora auct. non (Vahl) Alain | Henriettea fascicularis | Melastomataceae
|
| HENRI2 | Henriettea DC. | camasey | Melastomataceae
|
| HEFA2 | Henriettella fascicularis (Sw.) C. Wright ex Sauvalle | Henriettea fascicularis | Melastomataceae
|
| HEMA6 | Henriettella macfadyenii Triana | Henriettea macfadyenii | Melastomataceae
|
| HEME3 | Henriettella membranifolia Cogn. | Henriettea membranifolia | Melastomataceae
|
| HETR3 | Henriettella triflora auct. non (Vahl) Triana | Henriettea fascicularis | Melastomataceae
|
| HEBR9 | Henrya brevifolia Happ | Henrya insularis | Acanthaceae
|
| HEIN3 | Henrya insularis Nees ex Benth. | island renegade | Acanthaceae
|
| HENRY | Henrya Nees ex Benth. | henrya | Acanthaceae
|
| HEAC7 | Hepatica acuta (Pursh) Britt. | Hepatica nobilis var. acuta | Ranunculaceae
|
| HEAC4 | Hepatica acutiloba DC. | Hepatica nobilis var. acuta | Ranunculaceae
|
| HEAM8 | Hepatica americana (DC.) Ker-Gawl. | Hepatica nobilis var. obtusa | Ranunculaceae
|
| HEHE8 | Hepatica hepatica (L.) Karst. | Hepatica nobilis var. obtusa | Ranunculaceae
|
| HENOA | Hepatica nobilis Schreb. var. acuta (Pursh) Steyermark | sharplobe hepatica | Ranunculaceae
|
| HENOO | Hepatica nobilis Schreb. var. obtusa (Pursh) Steyermark | roundlobe hepatica | Ranunculaceae
|
| HENO2 | Hepatica nobilis Schreb. | hepatica | Ranunculaceae
|
| HETRA | Hepatica triloba Chaix var. acuta Pursh | Hepatica nobilis var. acuta | Ranunculaceae
|
| HETRA2 | Hepatica triloba Chaix var. americana DC. | Hepatica nobilis var. obtusa | Ranunculaceae
|
| HEPAT | Hepatica P. Mill. | hepatica | Ranunculaceae
|
| HEAD4 | Heppia adglutinata (Krempelh.) A. Massal. | | Heppiaceae
|
| HEBO7 | Heppia bolanderi (Tuck.) Vainio | Peltula bolanderi | Peltulaceae
|
| HECO25 | Heppia conchiloba Zahlbr. | | Heppiaceae
|
| HEDE11 | Heppia deserticola Zahlbr. | Peltula obscurans var. deserticola | Peltulaceae
|
| HEDE12 | Heppia despreauxii (Mont.) Tuck. | Heppia lutosa | Heppiaceae
|
| HEEU2 | Heppia euploca (Ach.) Vainio | Peltula euploca | Peltulaceae
|
| HEGU3 | Heppia guepinii (Delise) Nyl. | Peltula euploca | Peltulaceae
|
| HEHA5 | Heppia hassei Zahlbr. | Peltula obscurans var. hassei | Peltulaceae
|
| HELE10 | Heppia leptopholis Nyl. ex Hasse | Peltula patellata | Peltulaceae
|
| HELU6 | Heppia lutosa (Ach.) Nyl. | | Heppiaceae
|
| HEMA15 | Heppia macrospora de Lesd. | Heppia conchiloba | Heppiaceae
|
| HEPL4 | Heppia placodizans Zahlbr. | Peltula placodizans | Peltulaceae
|
| HEPO8 | Heppia polyphylla de Lesd. | Peltula euploca | Peltulaceae
|
| HEPO9 | Heppia polyspora Tuck. | Peltula patellata | Peltulaceae
|
| HERI5 | Heppia richardsii Herre | Peltula richardsii | Peltulaceae
|
| HETE24 | Heppia terrena Nyl. ex Hasse | Peltula patellata | Peltulaceae
|
| HETO5 | Heppia tortuosa (Nees) Vainio | Peltula tortuosa | Peltulaceae
|
| HEVI10 | Heppia virescens (Despr.) Nyl. | Heppia lutosa | Heppiaceae
|
| HEZA | Heppia zahlbruckneri Hasse | Peltula zahlbruckneri | Peltulaceae
|
| HEPPI | Heppia Nageli | heppia | Heppiaceae
|
| HELA4 | Heracleum lanatum Michx. | Heracleum maximum | Apiaceae
|
| HEMA17 | Heracleum mantegazzianum Sommier & Levier | giant hogweed | Apiaceae
|
| HEMA80 | Heracleum maximum Bartr. | common cowparsnip | Apiaceae
|
| HESIA | Heracleum sibiricum L. var. angustifolium Jacq. p.p. | Heracleum sphondylium ssp. sibiricum | Apiaceae
|
| HESI3 | Heracleum sibiricum L. | Heracleum sphondylium ssp. sibiricum | Apiaceae
|
| HESPM | Heracleum sphondylium L. ssp. montanum (Schleich. ex Gaudin) Briq. | Heracleum maximum | Apiaceae
|
| HESPS | Heracleum sphondylium L. ssp. sibiricum (L.) Simonkai | eltrot | Apiaceae
|
| HESPL | Heracleum sphondylium L. var. lanatum (Michx.) Dorn | Heracleum maximum | Apiaceae
|
| HESP6 | Heracleum sphondylium L. | eltrot | Apiaceae
|
| HERAC | Heracleum L. | cowparsnip | Apiaceae
|
| HECA17 | Herbertia caerulea (Herbert) Herbert | Herbertia lahue ssp. caerulea | Iridaceae
|
| HEDR5 | Herbertia drummondii (Graham) Small | Alophia drummondii | Iridaceae
|
| HELAC | Herbertia lahue (Molina) Goldblatt ssp. caerulea (Herbert) Goldblatt | prairienymph | Iridaceae
|
| HELA6 | Herbertia lahue (Molina) Goldblatt | prairienymph | Iridaceae
|
| HERBE | Herbertia Sweet | herbertia | Iridaceae
|
| HEADA | Herbertus aduncus (Dicks.) Gray ssp. aduncus | | Herbertaceae
|
| HEADT | Herbertus aduncus (Dicks.) Gray ssp. tenuis H. A. Mill. & E. B. Scott | | Herbertaceae
|
| HEAD5 | Herbertus aduncus (Dicks.) Gray | | Herbertaceae
|
| HEHA9 | Herbertus hawaiiensis H. A. Mill. | | Herbertaceae
|
| HEHI11 | Herbertus himalayanus (Steph.) H. A. Mill. | | Herbertaceae
|
| HESAA | Herbertus sakuraii (Warnst.) S. Hatt. ssp. articus Inoue & Steere | | Herbertaceae
|
| HESAS2 | Herbertus sakuraii (Warnst.) S. Hatt. ssp. sakuraii | | Herbertaceae
|
| HESA15 | Herbertus sakuraii (Warnst.) S. Hatt. | | Herbertaceae
|
| HESE9 | Herbertus sendtneri (Nees) Lindb. | | Herbertaceae
|
| HEST7 | Herbertus stramineus (Dumort.) Trevis. | | Herbertaceae
|
| HERBE2 | Herbertus Gray | | Herbertaceae
|
| HECR3 | Herissantia crispa (L.) Briz. | bladdermallow | Malvaceae
|
| HERIS | Herissantia Medik. | herissantia | Malvaceae
|
| HEAC9 | Heritiera actinophylla (F.M. Bailey) Kosterm. | black booyong | Sterculiaceae
|
| HELI9 | Heritiera littoralis Dryand. | | Sterculiaceae
|
| HERIT2 | Heritiera Ait. | | Sterculiaceae
|
| HEPA13 | Hermannia pauciflora S. Wats. | Santa Catalina burstwort | Sterculiaceae
|
| HETE9 | Hermannia texana Gray | Texas burstwort | Sterculiaceae
|
| HERMA | Hermannia L. | hermannia | Sterculiaceae
|
| HEEL5 | Hermbstaedtia elegans Moq. | Hermbstaedtia odorata | Amaranthaceae
|
| HEOD | Hermbstaedtia odorata (Burchell) T. Cooke | guineaflower | Amaranthaceae
|
| HERMB | Hermbstaedtia Reichenb. | hermbstaedtia | Amaranthaceae
|
| HEALP3 | Hermidium alipes S. Wats. var. pallidum C.L. Porter | Mirabilis alipes | Nyctaginaceae
|
| HEAL9 | Hermidium alipes S. Wats. | Mirabilis alipes | Nyctaginaceae
|
| HESO | Hernandia sonora L. | mago | Hernandiaceae
|
| HERNA | Hernandia L. | hernandia | Hernandiaceae
|
| HECI2 | Herniaria cinerea DC. | Herniaria hirsuta ssp. cinerea | Caryophyllaceae
|
| HEGL8 | Herniaria glabra L. | smooth rupturewort | Caryophyllaceae
|
| HEHIC | Herniaria hirsuta L. ssp. cinerea (DC.) Coutinho | hairy rupturewort | Caryophyllaceae
|
| HEHIH | Herniaria hirsuta L. ssp. hirsuta | hairy rupturewort | Caryophyllaceae
|
| HEHI7 | Herniaria hirsuta L. | hairy rupturewort | Caryophyllaceae
|
| HEIN4 | Herniaria incana Lam. | gray rupturewort | Caryophyllaceae
|
| HERNI | Herniaria L. | rupturewort | Caryophyllaceae
|
| HERO4 | Herpestis rotundifolia Gaertn. f. | Bacopa innominata | Scrophulariaceae
|
| HEAL11 | Herpetica alata (L.) Raf. | Senna alata | Fabaceae
|