| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| HERE7 | Hedysarum repens L. | Lespedeza repens | Fabaceae
|
| HESC16 | Hedysarum scoparium Fisch. & Mey. | sweetvetch | Fabaceae
|
| HESU | Hedysarum sulphurescens Rydb. | white sweetvetch | Fabaceae
|
| HETR2 | Hedysarum truncatum Eastw. | Hedysarum alpinum | Fabaceae
|
| HEUI | Hedysarum uintahense A. Nels. | Hedysarum occidentale var. occidentale | Fabaceae
|
| HEVI7 | Hedysarum violaceum L. | Lespedeza violacea | Fabaceae
|
| HEDYS | Hedysarum L. | sweetvetch | Fabaceae
|
| HELO8 | Heimia longipes (Gray) Cory | Nesaea longipes | Lythraceae
|
| HESA | Heimia salicifolia (Kunth) Link | shrubby yellowcrest | Lythraceae
|
| HEIMI | Heimia Link | heimia | Lythraceae
|
| HEHE9 | Heleastrum hemisphericum (Alexander) Shinners | Eurybia hemispherica | Asteraceae
|
| HEAMA | Helenium amarum (Raf.) H. Rock var. amarum | yellowdicks | Asteraceae
|
| HEAMB2 | Helenium amarum (Raf.) H. Rock var. badium (Gray ex S. Wats.) Waterfall | yellowdicks | Asteraceae
|
| HEAM | Helenium amarum (Raf.) H. Rock | yellowdicks | Asteraceae
|
| HEAM10 | Helenium amphilobum Gray | Helenium elegans var. amphilobum | Asteraceae
|
| HEAR2 | Helenium arizonicum Blake | Arizona sneezeweed | Asteraceae
|
| HEAUA | Helenium autumnale L. var. autumnale | common sneezeweed | Asteraceae
|
| HEAUC | Helenium autumnale L. var. canaliculatum (Lam.) Torr. & Gray | Helenium autumnale var. autumnale | Asteraceae
|
| HEAUG | Helenium autumnale L. var. grandiflorum (Nutt.) Torr. & Gray | fall sneezeweed | Asteraceae
|
| HEAUM | Helenium autumnale L. var. montanum (Nutt.) Fern. | mountain sneezeweed | Asteraceae
|
| HEAUP | Helenium autumnale L. var. parviflorum (Nutt.) Fern. | Helenium autumnale var. autumnale | Asteraceae
|
| HEAU | Helenium autumnale L. | common sneezeweed | Asteraceae
|
| HEBA | Helenium badium (Gray ex S. Wats.) Greene | Helenium amarum var. badium | Asteraceae
|
| HEBIF | Helenium bigelovii Gray var. festivum Jepson | Helenium bolanderi | Asteraceae
|
| HEBI | Helenium bigelovii Gray | Bigelow's sneezeweed | Asteraceae
|
| HEBO2 | Helenium bolanderi Gray | coastal sneezeweed | Asteraceae
|
| HEBR | Helenium brevifolium (Nutt.) Wood | shortleaf sneezeweed | Asteraceae
|
| HECA13 | Helenium campestre Small | oldfield sneezeweed | Asteraceae
|
| HECA24 | Helenium canaliculatum Lam. | Helenium autumnale var. autumnale | Asteraceae
|
| HECU6 | Helenium curtisii Gray | Helenium brevifolium | Asteraceae
|
| HEDE8 | Helenium decurrens (Less.) Vatke, non Moench | Helenium puberulum | Asteraceae
|
| HEDR2 | Helenium drummondii H. Rock | fringed sneezeweed | Asteraceae
|
| HEELA | Helenium elegans DC. var. amphilobum (Gray) Bierner | pretty sneezeweed | Asteraceae
|
| HEELE2 | Helenium elegans DC. var. elegans | pretty sneezeweed | Asteraceae
|
| HEEL | Helenium elegans DC. | pretty sneezeweed | Asteraceae
|
| HEFI2 | Helenium fimbriatum auct. non (Michx.) Gray | Helenium drummondii | Asteraceae
|
| HEFL | Helenium flexuosum Raf. | purplehead sneezeweed | Asteraceae
|
| HEFL9 | Helenium floridanum Fern. | Helenium flexuosum | Asteraceae
|
| HEGO2 | Helenium godfreyi Fern. | Helenium flexuosum | Asteraceae
|
| HEHE11 | Helenium helenium (Nutt.) Small | Helenium vernale | Asteraceae
|
| HEHO5 | Helenium hoopesii Gray | Hymenoxys hoopesii | Asteraceae
|
| HEIN8 | Helenium incisum (Torr. & Gray) Wood | Helenium pinnatifidum | Asteraceae
|
| HELA21 | Helenium latifolium P. Mill. | Helenium autumnale var. autumnale | Asteraceae
|
| HELI | Helenium linifolium Rydb. | slimleaf sneezeweed | Asteraceae
|
| HEMA12 | Helenium macranthum Rydb. | Helenium autumnale var. grandiflorum | Asteraceae
|
| HEMIM | Helenium microcephalum DC. var. microcephalum | smallhead sneezeweed | Asteraceae
|
| HEMIO2 | Helenium microcephalum DC. var. ooclinium (Gray) Bierner | smallhead sneezeweed | Asteraceae
|
| HEMI | Helenium microcephalum DC. | smallhead sneezeweed | Asteraceae
|
| HEMO9 | Helenium montanum Nutt. | Helenium autumnale var. montanum | Asteraceae
|
| HENU3 | Helenium nudiflorum Nutt. | Helenium flexuosum | Asteraceae
|
| HENU4 | Helenium nuttallii Gray | Helenium vernale | Asteraceae
|
| HEOO2 | Helenium ooclinium Gray | Helenium microcephalum var. ooclinium | Asteraceae
|
| HEPA15 | Helenium parviflorum Nutt. | Helenium autumnale var. autumnale | Asteraceae
|
| HEPI | Helenium pinnatifidum (Nutt.) Rydb. | southeastern sneezeweed | Asteraceae
|
| HEPO2 | Helenium �polyphyllum Small (pro sp.) | | Asteraceae
|
| HEPU2 | Helenium puberulum DC. | rosilla | Asteraceae
|
| HEQU | Helenium quadridentatum Labill. | longdisk sneezeweed | Asteraceae
|
| HERI4 | Helenium rivulare (Greene) Rydb. | Helenium bigelovii | Asteraceae
|
| HESE2 | Helenium setigerum (DC.) Britt. & Rusby | Amblyolepis setigera | Asteraceae
|
| HETE14 | Helenium tenuifolium Nutt. | Helenium amarum var. amarum | Asteraceae
|
| HETH | Helenium thurberi Gray | Thurber's sneezeweed | Asteraceae
|
| HEVE | Helenium vernale Walt. | savannah sneezeweed | Asteraceae
|
| HEVE5 | Helenium vernale auct. non Walt. | Helenium pinnatifidum | Asteraceae
|
| HEVI6 | Helenium virginicum Blake | Virginia sneezeweed | Asteraceae
|
| HELEN | Helenium L. | sneezeweed | Asteraceae
|
| HEFLF2 | Heleocharis flaccida (Reichenb.) Urban var. fuscescens K�kenth. | Eleocharis flavescens var. flavescens | Cyperaceae
|
| HEFL11 | Heleocharis flaccida (Reichenb.) Urban | Eleocharis flavescens var. flavescens | Cyperaceae
|
| HEAL10 | Heleochloa alopecuroides (Piller & Mitterp.) Host ex Roemer | Crypsis alopecuroides | Poaceae
|
| HESC8 | Heleochloa schoenoides (L.) Host ex Roemer | Crypsis schoenoides | Poaceae
|
| HECAC | Helianthella californica Gray var. californica | California helianthella | Asteraceae
|
| HECAN | Helianthella californica Gray var. nevadensis (Greene) Jepson | Nevada helianthella | Asteraceae
|
| HECAS2 | Helianthella californica Gray var. shastensis W.A. Weber | Shasta helianthella | Asteraceae
|
| HECA | Helianthella californica Gray | California helianthella | Asteraceae
|
| HECA2 | Helianthella castanea Greene | Mt. Diablo helianthella | Asteraceae
|
| HECO17 | Helianthella covillei A. Nels. | Enceliopsis covillei | Asteraceae
|
| HEGR16 | Helianthella grandiflora Torr. & Gray | Phoebanthus grandiflorus | Asteraceae
|
| HEMI2 | Helianthella microcephala (Gray) Gray | purpledisk helianthella | Asteraceae
|
| HEPA | Helianthella parryi Gray | Parry's dwarf-sunflower | Asteraceae
|
| HEPR6 | Helianthella pringlei Gray | Flourensia pringlei | Asteraceae
|
| HEQU2 | Helianthella quinquenervis (Hook.) Gray | fivenerve helianthella | Asteraceae
|
| HETE19 | Helianthella tenuifolia Torr. & Gray | Phoebanthus tenuifolius | Asteraceae
|
| HEUND | Helianthella uniflora (Nutt.) Torr. & Gray var. douglasii (Torr. & Gray) W.A. Weber | Douglas' helianthella | Asteraceae
|
| HEUNU | Helianthella uniflora (Nutt.) Torr. & Gray var. uniflora | oneflower helianthella | Asteraceae
|
| HEUN | Helianthella uniflora (Nutt.) Torr. & Gray | oneflower helianthella | Asteraceae
|
| HELIA | Helianthella Torr. & Gray | helianthella | Asteraceae
|
| HEAL6 | Helianthemum aldersonii Greene | Helianthemum scoparium | Cistaceae
|
| HEAR11 | Helianthemum arenicola Chapman | coastalsand frostweed | Cistaceae
|
| HEBI2 | Helianthemum bicknellii Fern. | hoary frostweed | Cistaceae
|
| HECAS3 | Helianthemum canadense (L.) Michx. var. sabulonum Fern. | Helianthemum canadense | Cistaceae
|
| HECA3 | Helianthemum canadense (L.) Michx. | longbranch frostweed | Cistaceae
|
| HECA27 | Helianthemum capitatum Nutt. ex Engelm. & Gray | Helianthemum rosmarinifolium | Cistaceae
|
| HECA4 | Helianthemum carolinianum (Walt.) Michx. | Carolina frostweed | Cistaceae
|
| HECO3 | Helianthemum corymbosum Michx. | pinebarren frostweed | Cistaceae
|
| HEDU | Helianthemum dumosum (Bickn.) Fern. | bushy frostweed | Cistaceae
|
| HEGE | Helianthemum georgianum Chapman | Georgia frostweed | Cistaceae
|
| HEGL | Helianthemum glomeratum (Lag.) Lag. ex Dunal | clustered frostweed | Cistaceae
|
| HEGR2 | Helianthemum greenei B.L. Robins. | island rushrose | Cistaceae
|
| HEGU | Helianthemum guttatum (L.) P. Mill. | Tuberaria guttata | Cistaceae
|
| HENA2 | Helianthemum nashii Britt. | Florida scrub frostweed | Cistaceae
|
| HEPR | Helianthemum propinquum Bickn. | low frostweed | Cistaceae
|
| HERO2 | Helianthemum rosmarinifolium Pursh | rosemary frostweed | Cistaceae
|