| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| HADIJ | Halimolobos diffusa (Gray) O.E. Schulz var. jaegeri (Munz) Rollins | Halimolobos jaegeri | Brassicaceae
|
| HADI4 | Halimolobos diffusa (Gray) O.E. Schulz | spreading fissurewort | Brassicaceae
|
| HAJA | Halimolobos jaegeri (Munz) Rollins | Mojave halimolobos | Brassicaceae
|
| HAMO | Halimolobos mollis (Hook.) Rollins | soft fissurewort | Brassicaceae
|
| HAPEL | Halimolobos perplexa (Henderson) Rollins var. lemhiensis C.L. Hitchc. | Lemhi halimolobos | Brassicaceae
|
| HAPEP | Halimolobos perplexa (Henderson) Rollins var. perplexa | perplexed halimolobos | Brassicaceae
|
| HAPE2 | Halimolobos perplexa (Henderson) Rollins | perplexed halimolobos | Brassicaceae
|
| HAVI3 | Halimolobos virgata (Nutt.) O.E. Schulz | rod halimolobos | Brassicaceae
|
| HAWH | Halimolobos whitedii (Piper) Rollins | Whited's fissurewort | Brassicaceae
|
| HALIM | Halimolobos Tausch | fissurewort | Brassicaceae
|
| HAFAH | Halliophytum fasciculatum (S. Wats.) I.M. Johnston var. hallii (Brandeg.) McMinn | Tetracoccus hallii | Euphorbiaceae
|
| HAFA | Halliophytum fasciculatum (S. Wats.) I.M. Johnston | Tetracoccus hallii | Euphorbiaceae
|
| HAHA6 | Halliophytum hallii (Brandeg.) I.M. Johnston | Tetracoccus hallii | Euphorbiaceae
|
| HABE2 | Halodule beaudettei (den Hartog) den Hartog | shoalweed | Cymodoceaceae
|
| HAUN3 | Halodule uninervis Boiss. | halodule | Cymodoceaceae
|
| HAWR | Halodule wrightii Aschers. | Halodule beaudettei | Cymodoceaceae
|
| HALOD | Halodule Endl. | halodule | Cymodoceaceae
|
| HAGL | Halogeton glomeratus (Bieb.) C.A. Mey. | saltlover | Chenopodiaceae
|
| HALOG | Halogeton C.A. Mey. | saltlover | Chenopodiaceae
|
| HAAS | Halophila aschersonii Ostenf. | Halophila baillonis | Hydrocharitaceae
|
| HABA | Halophila baillonis Aschers. ex Dickie | Florida Keys seagrass | Hydrocharitaceae
|
| HADE5 | Halophila decipiens Ostenf. | Caribbean seagrass | Hydrocharitaceae
|
| HAEN2 | Halophila engelmannii Aschers. | Engelmann's seagrass | Hydrocharitaceae
|
| HAHA3 | Halophila hawaiiana Doty & B.C. Stone | Hawai'i seagrass | Hydrocharitaceae
|
| HAJO | Halophila johnsonii Eiseman | Johnson's seagrass | Hydrocharitaceae
|
| HAMI5 | Halophila minor (Zoll.) den Hartog | seagrass | Hydrocharitaceae
|
| HAOVH | Halophila ovalis (R. Br.) Hook. f. ssp. hawaiiana (Doty & B.C. Stone) den Hartog | Halophila hawaiiana | Hydrocharitaceae
|
| HAOV | Halophila ovalis (R.Br.) Hook. f. | seagrass | Hydrocharitaceae
|
| HAOV2 | Halophila ovata Gaudich. | seagrass | Hydrocharitaceae
|
| HALOP | Halophila Thouars | seagrass | Hydrocharitaceae
|
| HACH5 | Haloragis chinensis (Lour.) Merrill | seaberry | Haloragaceae
|
| HAER2 | Haloragis erecta (Banks ex Murr.) Oken | erect seaberry | Haloragaceae
|
| HALOR | Haloragis J.R. & G. Forst. | seaberry | Haloragaceae
|
| HAHU2 | Haloscias hultenii (Fern.) Holub | Ligusticum scoticum ssp. hultenii | Apiaceae
|
| HAOC | Halostachys occidentalis S. Wats. | Allenrolfea occidentalis | Chenopodiaceae
|
| HAMA6 | Hamamelis macrophylla Pursh | Hamamelis virginiana | Hamamelidaceae
|
| HAVET | Hamamelis vernalis Sarg. var. tomentella (Rehd.) Palmer | Hamamelis vernalis | Hamamelidaceae
|
| HAVE2 | Hamamelis vernalis Sarg. | Ozark witchhazel | Hamamelidaceae
|
| HAVIH | Hamamelis virginiana L. var. henryi Jenne | Hamamelis virginiana | Hamamelidaceae
|
| HAVIM | Hamamelis virginiana L. var. macrophylla (Pursh) Nutt. | Hamamelis virginiana | Hamamelidaceae
|
| HAVIP | Hamamelis virginiana L. var. parvifolia Nutt. | Hamamelis virginiana | Hamamelidaceae
|
| HAVI4 | Hamamelis virginiana L. | American witchhazel | Hamamelidaceae
|
| HAMAM | Hamamelis L. | witchhazel | Hamamelidaceae
|
| HAHA9 | Hamatocactus hamatocanthus (Muhlph.) F.M. Kunth | | Cactaceae
|
| HAMAT3 | Hamatocactus Britton & Rose | hamatocactus | Cactaceae
|
| HALA8 | Hamatocaulis lapponicus (Norrl.) Heden�s | Lapland hamatocaulis moss | Amblystegiaceae
|
| HAVE70 | Hamatocaulis vernicosus (Mitt.) Heden�s | hamatocaulis moss | Amblystegiaceae
|
| HAMAT2 | Hamatocaulis Heden�s | hamatocaulis moss | Amblystegiaceae
|
| HAAX | Hamelia axillaris Sw. | balsamillo | Rubiaceae
|
| HAER3 | Hamelia erecta Jacq. | Hamelia patens | Rubiaceae
|
| HAPA3 | Hamelia patens Jacq. | scarletbush | Rubiaceae
|
| HAMEL | Hamelia Jacq. | hamelia | Rubiaceae
|
| HAPA11 | Hammarbya paludosa (L.) Kuntze | Malaxis paludosa | Orchidaceae
|
| HAAL4 | Hamulium alatum (L.) Cass. | Verbesina alata | Asteraceae
|
| HASP6 | Hancornia speciosa B. A. Gomes | mangabeira | Apocynaceae
|
| HANCO | Hancornia B. A. Gomes | hancornia | Apocynaceae
|
| HAMA8 | Hanguana malayana Merrill | | Hanguanaceae
|
| HANGU | Hanguana Blume | | Hanguanaceae
|
| HARE5 | Hapalanthus repens Jacq. | Callisia repens | Commelinaceae
|
| HALI7 | Hapalorchis lineatus (Lindl.) Schlechter | tropical ladies'-tresses | Orchidaceae
|
| HATE4 | Hapalorchis tenuis (Lindl.) Schlechter | Hapalorchis lineatus | Orchidaceae
|
| HAPAL | Hapalorchis Schlechter | hapalorchis | Orchidaceae
|
| HALY2 | Haplocarpha lyrata Harr. | harp onefruit | Asteraceae
|
| HAPLO10 | Haplocarpha Less. | onefruit | Asteraceae
|
| HAAN3 | Haplocladium angustifolium (Hampe & C. M�ll. in C. M�ll.) Broth. | Bryohaplocladium angustifolium | Leskeaceae
|
| HAMIL | Haplocladium microphyllum (Hedw.) Broth. var. lignicola (Kindb.) Reim. | Bryohaplocladium microphyllum | Leskeaceae
|
| HAMIO | Haplocladium microphyllum (Hedw.) Broth. var. obtusum (Grout) Crum | Bryohaplocladium microphyllum | Leskeaceae
|
| HAMI4 | Haplocladium microphyllum (Hedw.) Broth. | Bryohaplocladium microphyllum | Leskeaceae
|
| HAPR2 | Haplocladium praelongum (Schimp. ex Besch.) Crum | Rauiella praelonga | Thuidiaceae
|
| HAVI8 | Haplocladium virginianum (Brid.) Broth. | Bryohaplocladium virginianum | Leskeaceae
|
| HAPLO6 | Haplocladium (C. Muell.) C. Muell. | haplocladium | Thuidiaceae
|
| HAGRT | Haploesthes greggii Gray var. texana (Coult.) I.M. Johnston | Texas false broomweed | Asteraceae
|
| HAGR4 | Haploesthes greggii Gray | false broomweed | Asteraceae
|
| HAPLO | Haploesthes Gray | false broomweed | Asteraceae
|
| HATR4 | Haplohymenium triste (Ces. in De Not.) Kindb. | haplohymenium moss | Anomodontaceae
|
| HAPLO7 | Haplohymenium Dozy & Molk. | haplohymenium moss | Anomodontaceae
|
| HAHOH | Haplomitrium hookeri (Sm.) Nees var. hookeri | | Haplomitriaceae
|
| HAHO4 | Haplomitrium hookeri (Sm.) Nees | | Haplomitriaceae
|
| HAPLO5 | Haplomitrium Nees nom. cons. | | Haplomitriaceae
|
| HAAB | Haplopappus aberrans (A. Nels.) Hall | Tonestus aberrans | Asteraceae
|
| HAACT | Haplopappus acaulis (Nutt.) Gray ssp. typicus Hall | Stenotus acaulis var. acaulis | Asteraceae
|
| HAACG | Haplopappus acaulis (Nutt.) Gray var. glabratus D.C. Eat. | Stenotus acaulis var. glabratus | Asteraceae
|
| HAAC | Haplopappus acaulis (Nutt.) Gray | Stenotus acaulis var. acaulis | Asteraceae
|
| HAACB | Haplopappus acradenius (Greene) Blake ssp. bracteosus (Greene) Hall | Isocoma acradenia var. bracteosa | Asteraceae
|
| HAACE | Haplopappus acradenius (Greene) Blake ssp. eremophilus (Greene) Hall | Isocoma acradenia var. eremophila | Asteraceae
|
| HAAC2 | Haplopappus acradenius (Greene) Blake | Isocoma acradenia var. acradenia | Asteraceae
|
| HAAL5 | Haplopappus alpigenus Torr. & Gray | Oreostemma alpigenum var. alpigenum | Asteraceae
|
| HAAL3 | Haplopappus alpinus L.C. Anders. & Goodrich | Tonestus alpinus | Asteraceae
|
| HAAN | Haplopappus annuus (Rydb.) Cory | Rayjacksonia annua | Asteraceae
|
| HAAP | Haplopappus apargioides Gray | Pyrrocoma apargioides | Asteraceae
|
| HAAR | Haplopappus arborescens (Gray) Hall | Ericameria arborescens | Asteraceae
|
| HAARG | Haplopappus armerioides (Nutt.) Gray var. gramineus Welsh & F.G. Sm. | Stenotus armerioides var. gramineus | Asteraceae
|
| HAAR2 | Haplopappus armerioides (Nutt.) Gray | Stenotus armerioides var. armerioides | Asteraceae
|
| HAAU3 | Haplopappus aureus Gray | Rayjacksonia aurea | Asteraceae
|
| HABL7 | Haplopappus blephariphyllus Gray | Machaeranthera blephariphylla | Asteraceae
|
| HABLC2 | Haplopappus bloomeri Gray ssp. compactus Hall | Ericameria compacta | Asteraceae
|
| HABLS | Haplopappus bloomeri Gray ssp. sonnei (Gray) Hall | Ericameria bloomeri | Asteraceae
|
| HABLA | Haplopappus bloomeri Gray var. angustatus Gray | Ericameria bloomeri | Asteraceae
|
| HABLG | Haplopappus bloomeri Gray var. greenei (Gray) Cronq. | Ericameria greenei | Asteraceae
|
| HABLO | Haplopappus bloomeri Gray var. ophitidis J.T. Howell | Ericameria ophitidis | Asteraceae
|
| HABLS2 | Haplopappus bloomeri Gray var. sonnei (Gray) Greene | Ericameria bloomeri | Asteraceae
|