| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| HENIC | Helianthus niveus (Benth.) Brandeg. ssp. canescens (Gray) Heiser | showy sunflower | Asteraceae
|
| HENIT | Helianthus niveus (Benth.) Brandeg. ssp. tephrodes (Gray) Heiser | Algodones sunflower | Asteraceae
|
| HENI3 | Helianthus niveus (Benth.) Brandeg. | showy sunflower | Asteraceae
|
| HENUC | Helianthus nuttallii Torr. & Gray ssp. canadensis R.W. Long | Helianthus nuttallii ssp. nuttallii | Asteraceae
|
| HENUC2 | Helianthus nuttallii Torr. & Gray ssp. coloradensis (Cockerell) R.W. Long | Helianthus nuttallii ssp. nuttallii | Asteraceae
|
| HENUN | Helianthus nuttallii Torr. & Gray ssp. nuttallii | Nuttall's sunflower | Asteraceae
|
| HENUP | Helianthus nuttallii Torr. & Gray ssp. parishii (Gray) Heiser | Parish's sunflower | Asteraceae
|
| HENUR | Helianthus nuttallii Torr. & Gray ssp. rydbergii (Britt.) R.W. Long | Rydberg's sunflower | Asteraceae
|
| HENUR2 | Helianthus nuttallii Torr. & Gray var. rydbergii (Britt.) Boivin | Helianthus nuttallii ssp. rydbergii | Asteraceae
|
| HENUS | Helianthus nuttallii Torr. & Gray var. subtuberosus (Britt.) Boivin | Helianthus giganteus | Asteraceae
|
| HENU | Helianthus nuttallii Torr. & Gray | Nuttall's sunflower | Asteraceae
|
| HEOCO | Helianthus occidentalis Riddell ssp. occidentalis | fewleaf sunflower | Asteraceae
|
| HEOCP | Helianthus occidentalis Riddell ssp. plantagineus (Torr. & Gray) Shinners | fewleaf sunflower | Asteraceae
|
| HEOCD | Helianthus occidentalis Riddell var. dowellianus (M.A. Curtis) Torr. & Gray | Helianthus occidentalis ssp. occidentalis | Asteraceae
|
| HEOCP2 | Helianthus occidentalis Riddell var. plantagineus Torr. & Gray | Helianthus occidentalis ssp. plantagineus | Asteraceae
|
| HEOC2 | Helianthus occidentalis Riddell | fewleaf sunflower | Asteraceae
|
| HEOR4 | Helianthus orgyalis DC. | Helianthus salicifolius | Asteraceae
|
| HEOR | Helianthus �orgyaloides Cockerell (pro sp.) | | Asteraceae
|
| HEPA2 | Helianthus paradoxus Heiser | paradox sunflower | Asteraceae
|
| HEPA23 | Helianthus parishii Gray | Helianthus nuttallii ssp. parishii | Asteraceae
|
| HEPAP2 | Helianthus pauciflorus Nutt. ssp. pauciflorus | stiff sunflower | Asteraceae
|
| HEPAS | Helianthus pauciflorus Nutt. ssp. subrhomboideus (Rydb.) O. Spring & E. Schilling | stiff sunflower | Asteraceae
|
| HEPAS2 | Helianthus pauciflorus Nutt. var. subrhomboideus (Rydb.) Cronq. | Helianthus pauciflorus ssp. subrhomboideus | Asteraceae
|
| HEPA19 | Helianthus pauciflorus Nutt. | stiff sunflower | Asteraceae
|
| HEPEF | Helianthus petiolaris Nutt. ssp. fallax Heiser | prairie sunflower | Asteraceae
|
| HEPEP | Helianthus petiolaris Nutt. ssp. petiolaris | prairie sunflower | Asteraceae
|
| HEPEC | Helianthus petiolaris Nutt. var. canescens Gray | Helianthus niveus ssp. canescens | Asteraceae
|
| HEPEF2 | Helianthus petiolaris Nutt. var. fallax (Heiser) B.L. Turner | Helianthus petiolaris ssp. fallax | Asteraceae
|
| HEPE | Helianthus petiolaris Nutt. | prairie sunflower | Asteraceae
|
| HEPI7 | Helianthus pilosus Tausch | Helianthus doronicoides | Asteraceae
|
| HEPO3 | Helianthus porteri (Gray) Pruski | Porter's sunflower | Asteraceae
|
| HEPRH | Helianthus praecox Engelm. & Gray ssp. hirtus (Heiser) Heiser | Texas sunflower | Asteraceae
|
| HEPRP | Helianthus praecox Engelm. & Gray ssp. praecox | Texas sunflower | Asteraceae
|
| HEPRR | Helianthus praecox Engelm. & Gray ssp. runyonii (Heiser) Heiser | Runyon's sunflower | Asteraceae
|
| HEPRR2 | Helianthus praecox Engelm. & Gray var. runyonii (Heiser) B.L. Turner | Helianthus praecox ssp. runyonii | Asteraceae
|
| HEPR2 | Helianthus praecox Engelm. & Gray | Texas sunflower | Asteraceae
|
| HEPR5 | Helianthus praetermissus E.E. Wats. | New Mexico sunflower | Asteraceae
|
| HEPU3 | Helianthus pumilus Nutt. | little sunflower | Asteraceae
|
| HEQU4 | Helianthus quinquenervis Hook. | Helianthella quinquenervis | Asteraceae
|
| HERA | Helianthus radula (Pursh) Torr. & Gray | rayless sunflower | Asteraceae
|
| HERE8 | Helianthus reindutus (Steele) E.E. Wats. | Helianthus laevigatus | Asteraceae
|
| HERE5 | Helianthus resinosus Small | resindot sunflower | Asteraceae
|
| HERIL | Helianthus rigidus (Cass.) Desf. ssp. laetiflorus (Rydb.) Heiser | Helianthus pauciflorus ssp. subrhomboideus | Asteraceae
|
| HERIS2 | Helianthus rigidus (Cass.) Desf. ssp. subrhomboideus (Rydb.) Heiser | Helianthus pauciflorus ssp. subrhomboideus | Asteraceae
|
| HERIS3 | Helianthus rigidus (Cass.) Desf. var. subrhomboideus (Rydb.) Cronq. | Helianthus pauciflorus ssp. subrhomboideus | Asteraceae
|
| HERI2 | Helianthus rigidus (Cass.) Desf. | Helianthus pauciflorus ssp. pauciflorus | Asteraceae
|
| HERY80 | Helianthus rydbergii Britt. | Helianthus nuttallii ssp. rydbergii | Asteraceae
|
| HESA2 | Helianthus salicifolius A. Dietr. | willowleaf sunflower | Asteraceae
|
| HESA6 | Helianthus saxicola Small | Helianthus strumosus | Asteraceae
|
| HESC13 | Helianthus scaberrimus Ell. | Helianthus laetiflorus | Asteraceae
|
| HESC3 | Helianthus schweinitzii Torr. & Gray | Schweinitz's sunflower | Asteraceae
|
| HESC12 | Helianthus scrophulariifolius Britt. | Helianthus decapetalus | Asteraceae
|
| HESI | Helianthus silphioides Nutt. | rosinweed sunflower | Asteraceae
|
| HESI2 | Helianthus simulans E.E. Wats. | muck sunflower | Asteraceae
|
| HESM | Helianthus smithii Heiser | Smith's sunflower | Asteraceae
|
| HEST4 | Helianthus stenophyllus (Torr. & Gray) E.E. Wats. | Helianthus hirsutus | Asteraceae
|
| HEST | Helianthus strumosus L. | paleleaf woodland sunflower | Asteraceae
|
| HESU11 | Helianthus subrhomboideus Rydb. | Helianthus pauciflorus ssp. subrhomboideus | Asteraceae
|
| HESU10 | Helianthus subtuberosus (Britt.) Britt. | Helianthus giganteus | Asteraceae
|
| HETE15 | Helianthus tephrodes Gray | Helianthus niveus ssp. tephrodes | Asteraceae
|
| HETO4 | Helianthus tomentosus Michx. | Helianthus tuberosus | Asteraceae
|
| HETO3 | Helianthus tomentosus auct. non Michx. | Helianthus resinosus | Asteraceae
|
| HETR8 | Helianthus tracheliifolius P. Mill. | Helianthus decapetalus | Asteraceae
|
| HETUS2 | Helianthus tuberosus L. var. subcanescens Gray | Helianthus tuberosus | Asteraceae
|
| HETU | Helianthus tuberosus L. | Jerusalem artichoke | Asteraceae
|
| HEUN6 | Helianthus uniflorus Nutt. | Helianthella uniflora var. uniflora | Asteraceae
|
| HEVA | Helianthus validus E.E. Wats. | Helianthus giganteus | Asteraceae
|
| HEVE3 | Helianthus �verticillatus E.E. Wats. (pro sp.) | | Asteraceae
|
| HEVE6 | Helianthus vestitus E.E. Wats. | Helianthus debilis ssp. vestitus | Asteraceae
|
| HELIA3 | Helianthus L. | sunflower | Asteraceae
|
| HEBR6 | Helichrysum bracteatum (Vent.) Andr. | bracted strawflower | Asteraceae
|
| HEFO4 | Helichrysum foetidum (L.) Cass. | stinking strawflower | Asteraceae
|
| HEFO7 | Helichrysum formosissimum Sch. Bip. | everlasting-flower | Asteraceae
|
| HEPE8 | Helichrysum petiolare Hilliard & Burtt | | Asteraceae
|
| HEPE9 | Helichrysum petiolatum (L.) DC. | Helichrysum petiolare | Asteraceae
|
| HELIC4 | Helichrysum P. Mill. | strawflower | Asteraceae
|
| HEBI4 | Heliconia bihai (L.) L. | macawflower | Heliconiaceae
|
| HECA10 | Heliconia caribaea Lam. | lobsterclaw | Heliconiaceae
|
| HECO31 | Heliconia collinsiana Griggs | platanillo | Heliconiaceae
|
| HEEL7 | Heliconia elongata Griggs | Heliconia wagneriana | Heliconiaceae
|
| HEHU3 | Heliconia humilis (Aubl.) Jacq. | Heliconia bihai | Heliconiaceae
|
| HELA12 | Heliconia latispatha Benth. | expanded lobsterclaw | Heliconiaceae
|
| HEME4 | Heliconia metallica Planch. & Linden ex Hook. | shining bird of paradise | Heliconiaceae
|
| HEPS2 | Heliconia psittacorum L. f. | parakeetflower | Heliconiaceae
|
| HESU7 | Heliconia subulata Ruiz & Pav�n | Guatemalan bird of paradise | Heliconiaceae
|
| HEWA2 | Heliconia wagneriana Peterson | | Heliconiaceae
|
| HELIC2 | Heliconia L. | heliconia | Heliconiaceae
|
| HEAP2 | Helicteres apetala Jacq. | Sterculia apetala | Sterculiaceae
|
| HEJA | Helicteres jamaicensis Jacq. | screwtree | Sterculiaceae
|
| HELIC3 | Helicteres L. | helicteres | Sterculiaceae
|
| HEHO8 | Helictotrichon hookeri (Scribn.) Henr. | spikeoat | Poaceae
|
| HEMO3 | Helictotrichon mortonianum (Scribn.) Henr. | Morton's alpineoatgrass | Poaceae
|
| HEPU4 | Helictotrichon pubescens (Huds.) Bess. ex Pilger | downy alpineoatgrass | Poaceae
|
| HESC17 | Helictotrichon scabrivalve (Trin.) G. Tucker | Amphibromus scabrivalvis | Poaceae
|
| HELIC | Helictotrichon Bess. ex J.A. & J.H. Schultes | alpineoatgrass | Poaceae
|
| HEPA3 | Helietta parvifolia (Gray ex Hemsl.) Benth. | barreta | Rutaceae
|
| HELIE | Helietta Tul. | helietta | Rutaceae
|
| HEPO4 | Heliocarpus popayanensis Kunth | white moho | Tiliaceae
|
| HELIO | Heliocarpus L. | heliocarpus | Tiliaceae
|
| HEAN11 | Heliomeris annua (M.E. Jones) Cockerell | Heliomeris longifolia var. annua | Asteraceae
|
| HECI4 | Heliomeris ciliata (Robins. & Greenm.) Yates | hairy false goldeneye | Asteraceae
|