| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| HAPH2 | Haplopappus phyllocephalus DC. | Rayjacksonia phyllocephala | Asteraceae
|
| HAPI | Haplopappus pinifolius Gray | Ericameria pinifolia | Asteraceae
|
| HAPL | Haplopappus pluriflorus (Torr. & Gray) Hall | Isocoma pluriflora | Asteraceae
|
| HAPR | Haplopappus propinquus Blake | Ericameria brachylepis | Asteraceae
|
| HAPY | Haplopappus pygmaeus (Torr. & Gray) Gray | Tonestus pygmaeus | Asteraceae
|
| HARAB | Haplopappus racemosus (Nutt.) Torr. ssp. brachycephalus (A. Nels.) Hall | Pyrrocoma racemosa var. paniculata | Asteraceae
|
| HARAC | Haplopappus racemosus (Nutt.) Torr. ssp. congestus (Greene) Hall | Pyrrocoma racemosa var. congesta | Asteraceae
|
| HARAD | Haplopappus racemosus (Nutt.) Torr. ssp. duriuscula (Greene) Hall | Pyrrocoma racemosa var. paniculata | Asteraceae
|
| HARAG2 | Haplopappus racemosus (Nutt.) Torr. ssp. glomeratus (Nutt.) Hall | Pyrrocoma racemosa var. paniculata | Asteraceae
|
| HARAH | Haplopappus racemosus (Nutt.) Torr. ssp. halophilus (Greene) Hall | Pyrrocoma racemosa var. paniculata | Asteraceae
|
| HARAL2 | Haplopappus racemosus (Nutt.) Torr. ssp. liatriformis (Greene) Keck | Pyrrocoma liatriformis | Asteraceae
|
| HARAL | Haplopappus racemosus (Nutt.) Torr. ssp. lucidus Keck | Pyrrocoma lucida | Asteraceae
|
| HARAP | Haplopappus racemosus (Nutt.) Torr. ssp. pinetorum Keck | Pyrrocoma racemosa var. pinetorum | Asteraceae
|
| HARAP2 | Haplopappus racemosus (Nutt.) Torr. ssp. prionophyllus (Greene) Hall | Pyrrocoma racemosa var. paniculata | Asteraceae
|
| HARAS | Haplopappus racemosus (Nutt.) Torr. ssp. sessiliflorus (Greene) Hall | Pyrrocoma racemosa var. sessiliflora | Asteraceae
|
| HARAG | Haplopappus racemosus (Nutt.) Torr. var. glomerellus (Nutt.) Gray | Pyrrocoma racemosa var. paniculata | Asteraceae
|
| HARAP3 | Haplopappus racemosus (Nutt.) Torr. var. prionophyllus (Greene) Welsh | Pyrrocoma racemosa var. paniculata | Asteraceae
|
| HARAS2 | Haplopappus racemosus (Nutt.) Torr. var. sessiliflorus (Greene) Welsh | Pyrrocoma racemosa var. sessiliflora | Asteraceae
|
| HARA | Haplopappus racemosus (Nutt.) Torr. | Pyrrocoma racemosa var. racemosa | Asteraceae
|
| HARA2 | Haplopappus radiatus (Nutt.) Cronq. | Pyrrocoma radiata | Asteraceae
|
| HARA3 | Haplopappus ravenii R.C. Jackson | Machaeranthera gracilis | Asteraceae
|
| HARE3 | Haplopappus resinosus (Nutt.) Gray | Ericameria resinosa | Asteraceae
|
| HARI | Haplopappus rigidifolius E.B. Sm. | Croptilon rigidifolium | Asteraceae
|
| HARU | Haplopappus rusbyi (Greene) Cronq. | Isocoma rusbyi | Asteraceae
|
| HARY | Haplopappus rydbergii Blake | Ericameria obovata | Asteraceae
|
| HASA3 | Haplopappus salicinus Blake | Hesperodoria salicina | Asteraceae
|
| HASCH | Haplopappus scopulorum (M.E. Jones) Blake var. hirtellus Blake | Hesperodoria scopulorum | Asteraceae
|
| HASC | Haplopappus scopulorum (M.E. Jones) Blake | Hesperodoria scopulorum | Asteraceae
|
| HASPA | Haplopappus spinulosus (Pursh) DC. ssp. australis (Greene) Hall | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| HASPC | Haplopappus spinulosus (Pursh) DC. ssp. cotulus (Small) Hall | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| HASPG4 | Haplopappus spinulosus (Pursh) DC. ssp. glaberrimus (Rydb.) Hall | Machaeranthera pinnatifida ssp. pinnatifida var. glaberrima | Asteraceae
|
| HASPL | Haplopappus spinulosus (Pursh) DC. ssp. laevis (Woot. & Standl.) Hall | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| HASPC2 | Haplopappus spinulosus (Pursh) DC. var. canescens Gray | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| HASPC3 | Haplopappus spinulosus (Pursh) DC. var. chihuahuanus (B.L. Turner & Hartman) Gandhi | Machaeranthera pinnatifida ssp. pinnatifida var. chihuahuana | Asteraceae
|
| HASPG3 | Haplopappus spinulosus (Pursh) DC. var. glaber Gray | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| HASPG2 | Haplopappus spinulosus (Pursh) DC. var. glaberrimus (Rydb.) Blake | Machaeranthera pinnatifida ssp. pinnatifida var. glaberrima | Asteraceae
|
| HASPG | Haplopappus spinulosus (Pursh) DC. var. gooddingii (A. Nels.) Blake | Machaeranthera pinnatifida ssp. gooddingii var. gooddingii | Asteraceae
|
| HASPP | Haplopappus spinulosus (Pursh) DC. var. paradoxa (B.L. Turner & Hartman) Cronq. | Machaeranthera pinnatifida ssp. gooddingii var. paradoxa | Asteraceae
|
| HASPT | Haplopappus spinulosus (Pursh) DC. var. turbinellus (Rydb.) Blake | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| HASP3 | Haplopappus spinulosus (Pursh) DC. | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| HASQG | Haplopappus squarrosus Hook. & Arn. ssp. grindelioides (DC.) Keck | Hazardia squarrosa var. grindelioides | Asteraceae
|
| HASQO | Haplopappus squarrosus Hook. & Arn. ssp. obtusus (Greene) Hall | Hazardia squarrosa var. obtusa | Asteraceae
|
| HASQS | Haplopappus squarrosus Hook. & Arn. ssp. stenolepis Hall | Hazardia stenolepis | Asteraceae
|
| HASQ | Haplopappus squarrosus Hook. & Arn. | Hazardia squarrosa var. squarrosa | Asteraceae
|
| HAST | Haplopappus stenophyllus Gray | Stenotus stenophyllus | Asteraceae
|
| HASU2 | Haplopappus subviscosus (Greene) Blake | Pyrrocoma lanceolata var. subviscosa | Asteraceae
|
| HASU | Haplopappus suffruticosus (Nutt.) Gray | Ericameria suffruticosa | Asteraceae
|
| HATE | Haplopappus tenuisectus (Greene) Blake | Isocoma tenuisecta | Asteraceae
|
| HATE5 | Haplopappus texensis R.C. Jackson | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| HATR3 | Haplopappus trianthus Blake | Xylothamia triantha | Asteraceae
|
| HAUNG | Haplopappus uniflorus (Hook.) Torr. & Gray ssp. gossypinus (Greene) Hall | Pyrrocoma uniflora var. gossypina | Asteraceae
|
| HAUNH2 | Haplopappus uniflorus (Hook.) Torr. & Gray ssp. howellii (Gray) Hall | Pyrrocoma uniflora var. uniflora | Asteraceae
|
| HAUNL | Haplopappus uniflorus (Hook.) Torr. & Gray ssp. linearis Keck | Pyrrocoma linearis | Asteraceae
|
| HAUNT | Haplopappus uniflorus (Hook.) Torr. & Gray ssp. typicus Hall | Pyrrocoma uniflora var. uniflora | Asteraceae
|
| HAUNH | Haplopappus uniflorus (Hook.) Torr. & Gray var. howellii (Gray) M.E. Peck | Pyrrocoma uniflora var. uniflora | Asteraceae
|
| HAUN2 | Haplopappus uniflorus (Hook.) Torr. & Gray | Pyrrocoma uniflora var. uniflora | Asteraceae
|
| HAVAG | Haplopappus validus (Rydb.) Cory ssp. graniticus E.B. Sm. | Croptilon hookerianum var. graniticum | Asteraceae
|
| HAVAT | Haplopappus validus (Rydb.) Cory ssp. torreyi E.B. Sm. | Croptilon hookerianum var. hookerianum | Asteraceae
|
| HAVA | Haplopappus validus (Rydb.) Cory | Croptilon hookerianum var. validum | Asteraceae
|
| HAVEF | Haplopappus venetus (Kunth) Blake ssp. furfuraceus (Greene) Hall | Isocoma menziesii var. decumbens | Asteraceae
|
| HAVEO | Haplopappus venetus (Kunth) Blake ssp. oxyphyllus (Greene) Hall | Isocoma menziesii var. menziesii | Asteraceae
|
| HAVEV | Haplopappus venetus (Kunth) Blake ssp. vernonioides (Nutt.) Hall | Isocoma menziesii var. vernonioides | Asteraceae
|
| HAVEA | Haplopappus venetus (Kunth) Blake var. argutus (Greene) Keck | Isocoma arguta | Asteraceae
|
| HAVES2 | Haplopappus venetus (Kunth) Blake var. sedoides (Greene) Munz | Isocoma menziesii var. sedoides | Asteraceae
|
| HAWA2 | Haplopappus wardii (Gray) Dorn | Oonopsis wardii | Asteraceae
|
| HAWAR | Haplopappus watsonii Gray var. rydbergii (Blake) Welsh | Ericameria obovata | Asteraceae
|
| HAWA | Haplopappus watsonii Gray | Ericameria watsonii | Asteraceae
|
| HAWHD | Haplopappus whitneyi Gray ssp. discoideus (J.T. Howell) Keck | Hazardia whitneyi var. discoidea | Asteraceae
|
| HAWH2 | Haplopappus whitneyi Gray | Hazardia whitneyi var. whitneyi | Asteraceae
|
| HAZI | Haplopappus zionis L.C. Anders. | Ericameria zionis | Asteraceae
|
| HAPLO11 | Haplopappus Cass. | haplopappus | Asteraceae
|
| HACIC | Haplophyton cimicidum A. DC. var. crooksii L. Benson | Haplophyton crooksii | Apocynaceae
|
| HACI9 | Haplophyton cimicidum auct. non A. DC. | Haplophyton crooksii | Apocynaceae
|
| HACR3 | Haplophyton crooksii (L. Benson) L. Benson | cockroachplant | Apocynaceae
|
| HAPLO3 | Haplophyton A. DC. | haplophyton | Apocynaceae
|
| HABRM | Haplostachys bryanii Sherff var. microdonta Sherff | Haplostachys bryanii | Lamiaceae
|
| HABRR | Haplostachys bryanii Sherff var. robusta Sherff | Haplostachys bryanii | Lamiaceae
|
| HABR2 | Haplostachys bryanii Sherff | Molokai islandmint | Lamiaceae
|
| HAHAA | Haplostachys haplostachya (Gray) St. John var. angustifolia (Sherff) St. John | Haplostachys haplostachya | Lamiaceae
|
| HAHAL | Haplostachys haplostachya (Gray) St. John var. leptostachya (Hbd.) St. John | Haplostachys haplostachya | Lamiaceae
|
| HAHA4 | Haplostachys haplostachya (Gray) St. John | honohono | Lamiaceae
|
| HALIR | Haplostachys linearifolia (Drake) Sherff var. rosmarinifolia (Hbd.) Sherff | Haplostachys linearifolia | Lamiaceae
|
| HALI4 | Haplostachys linearifolia (Drake) Sherff | woodland islandmint | Lamiaceae
|
| HAMU2 | Haplostachys munroi Forbes | Lanai islandmint | Lamiaceae
|
| HATR2 | Haplostachys truncata (Gray) Hbd. | Maui islandmint | Lamiaceae
|
| HAPLO4 | Haplostachys (Gray) Hbd. | haplostachys | Lamiaceae
|
| HATR | Harbouria trachypleura (Gray) Coult. & Rose | whiskbroom parsley | Apiaceae
|
| HARBO | Harbouria Coult. & Rose | harbouria | Apiaceae
|
| HAPAA | Harpagonella palmeri Gray var. arizonica I.M. Johnston | Arizona grapplinghook | Boraginaceae
|
| HAPAP2 | Harpagonella palmeri Gray var. palmeri | Palmer's grapplinghook | Boraginaceae
|
| HAPA7 | Harpagonella palmeri Gray | Palmer's grapplinghook | Boraginaceae
|
| HARPA | Harpagonella Gray | grapplinghook | Boraginaceae
|
| HAOVI | Harpalejeunea ovata (Hook.) Schiffn. ssp. integra R. M. Schust. | | Lejeuneaceae
|
| HAOV3 | Harpalejeunea ovata (Hook.) Schiffn. | | Lejeuneaceae
|
| HAST8 | Harpalejeunea stricta (Lindenb. & Gottsche) Steph. | | Lejeuneaceae
|
| HARPA2 | Harpalejeunea (Spruce) Schiffn. | | Lejeuneaceae
|
| HADR3 | Harpanthus drummondii (Taylor) Grolle | | Geocalycaceae
|
| HAFL9 | Harpanthus flotovianus (Nees) Nees | | Geocalycaceae
|
| HASC3 | Harpanthus scutatus (F. Weber & D. Mohr) Spruce | | Geocalycaceae
|
| HARPA3 | Harpanthus Nees | | Geocalycaceae
|
| HAFL5 | Harperella fluviatilis Rose | Ptilimnium nodosum | Apiaceae
|