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Plant List
Indexed Alphabetically by Common Name
H, I, J, K
For a list of plants indexed by Scientific Name, click here
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| National Common Name | Scientific Name with Author | Symbol | Family | |
| ha'a | Antidesma platyphyllum Mann | ANPL2 | Euphorbiaceae | |
| ha'a | Antidesma platyphyllum Mann var. platyphyllum | ANPLP | Euphorbiaceae | |
| hackberry | Celtis L. | CELTI | Ulmaceae | |
| Hagen's bryum moss | Bryum hagenii Limpr. | BRHA3 | Bryaceae | |
| haggarbush | Clerodendrum aculeatum (L.) Schlecht. | CLAC2 | Verbenaceae | |
| haha'aiakamanu | Clermontia fauriei Levl. | CLFA | Campanulaceae | |
| hahala | Cyrtandra garnotiana Gaud. | CYGA2 | Gesneriaceae | |
| Haid's amygdalaria lichen | Amygdalaria haidensis Brodo & Hertel | AMHA | Porpidiaceae | |
| hairgrass | Aira L. | AIRA | Poaceae | |
| hairlike sedge | Carex capillaris L. | CACA12 | Cyperaceae | |
| hairpin banksia | Banksia spinulosa Sm. | BASP6 | Proteaceae | |
| hairsedge | Bulbostylis Kunth | BULBO | Cyperaceae | |
| hairy angelica | Angelica venenosa (Greenway) Fern. | ANVE | Apiaceae | |
| hairy arnica | Arnica mollis Hook. | ARMO4 | Asteraceae | |
| hairy ayenia | Ayenia pilosa Cristobal | AYPI | Sterculiaceae | |
| hairy balsamroot | Balsamorhiza hookeri (Hook.) Nutt. var. hirsuta (Nutt.) A. Nels. | BAHOH | Asteraceae | |
| hairy balsamroot | Balsamorhiza hookeri (Hook.) Nutt. var. hispidula (Sharp) Cronq. | BAHOH2 | Asteraceae | |
| hairy beggarticks | Bidens pilosa L. | BIPI | Asteraceae | |
| hairy bird's beak | Cordylanthus pilosus Gray ssp. pilosus | COPIP | Scrophulariaceae | |
| hairy bird's beak | Cordylanthus pilosus Gray ssp. trifidus (Robins. & Greenm.) Chuang & Heckard | COPIT | Scrophulariaceae | |
| hairy bird's-beak | Cordylanthus pilosus Gray | COPI2 | Scrophulariaceae | |
| hairy bittercress | Cardamine hirsuta L. | CAHI3 | Brassicaceae | |
| hairy bluestem | Andropogon longiberbis Hack. | ANLO2 | Poaceae | |
| hairy brome | Bromus ramosus Huds. | BRRA3 | Poaceae | |
| hairy bugseed | Corispermum villosum Rydb. | COVI5 | Chenopodiaceae | |
| hairy ceanothus | Ceanothus oliganthus Nutt. | CEOL | Rhamnaceae | |
| hairy chaffhead | Carphephorus paniculatus (J.F. Gmel.) Herbert | CAPA53 | Asteraceae | |
| hairy clematis | Clematis hirsutissima Pursh | CLHI | Ranunculaceae | |
| hairy clematis | Clematis hirsutissima Pursh var. hirsutissima | CLHIH | Ranunculaceae | |
| hairy cup orchid | Brachionidium ciliolatum Garay | BRCI4 | Orchidaceae | |
| hairy cyanea | Cyanea pilosa Gray | CYPI4 | Campanulaceae | |
| hairy cyanea | Cyanea pilosa Gray ssp. longipedunculata (Rock) Lammers | CYPIL | Campanulaceae | |
| hairy cyanea | Cyanea pilosa Gray ssp. pilosa | CYPIP | Campanulaceae | |
| hairy dozedaisy | Aphanostephus pilosus Buckl. | APPI | Asteraceae | |
| hairy false cloak fern | Argyrochosma incana (K. Presl) Windham | ARIN11 | Pteridaceae | |
| hairy five eyes | Chamaesaracha sordida (Dunal) Gray | CHSO | Solanaceae | |
| hairy flatsedge | Cyperus dentoniae G. Tucker | CYDE10 | Cyperaceae | |
| hairy flowering fern | Anemia hirsuta (L.) Sw. | ANHI2 | Anemiaceae | |
| hairy grama | Bouteloua hirsuta Lag. | BOHI2 | Poaceae | |
| hairy grama | Bouteloua hirsuta Lag. var. hirsuta | BOHIH | Poaceae | |
| hairy Indian mallow | Abutilon grandifolium (Willd.) Sweet | ABGR3 | Malvaceae | |
| hairy Indian paintbrush | Castilleja tenuis (Heller) Chuang & Heckard | CATE26 | Scrophulariaceae | |
| hairy jointvetch | Aeschynomene villosa Poir. | AEVI2 | Fabaceae | |
| hairy joyweed | Alternanthera flavogrisea Urban | ALFL5 | Amaranthaceae | |
| hairy knight's-spur | Consolida pubescens (DC.) Soó | COPU21 | Ranunculaceae | |
| hairy lady's mantle | Alchemilla monticola Opiz | ALMO4 | Rosaceae | |
| hairy lipfern | Cheilanthes lanosa (Michx.) D.C. Eat. | CHLA2 | Pteridaceae | |
| hairy manzanita | Arctostaphylos columbiana Piper | ARCO3 | Ericaceae | |
| hairy marshmallow | Althaea hirsuta L. | ALHI2 | Malvaceae | |
| hairy mountain mahogany | Cercocarpus montanus Raf. var. paucidentatus (S. Wats.) F.L. Martin | CEMOP | Rosaceae | |
| hairy pagoda-plant | Blephilia hirsuta (Pursh) Benth. | BLHI | Lamiaceae | |
| hairy pagoda-plant | Blephilia hirsuta (Pursh) Benth. var. glabrata Fern. | BLHIG | Lamiaceae | |
| hairy pagoda-plant | Blephilia hirsuta (Pursh) Benth. var. hirsuta | BLHIH | Lamiaceae | |
| hairy ragweed | Ambrosia canescens Gray | AMCA7 | Asteraceae | |
| hairy rockcress | Arabis hirsuta (L.) Scop. | ARHI | Brassicaceae | |
| hairy rockcress | Arabis hirsuta (L.) Scop. var. hirsuta | ARHIH | Brassicaceae | |
| hairy rockrose | Cistus incanus L. | CIIN80 | Cistaceae | |
| hairy rockrose | Cistus incanus L. ssp. corsicus (Loisel.) Heywood | CIINC | Cistaceae | |
| hairy rockrose | Cistus incanus L. ssp. incanus | CIINI | Cistaceae | |
| hairy sandmat | Chamaesyce villifera (Scheele) Small | CHVI17 | Euphorbiaceae | |
| hairy sedge | Carex lacustris Willd. | CALA16 | Cyperaceae | |
| hairy sensitive pea | Chamaecrista pilosa (L.) Greene | CHPI5 | Fabaceae | |
| hairy smotherweed | Bassia hirsuta (L.) Aschers. | BAHI3 | Chenopodiaceae | |
| hairy spotflower | Acmella pilosa R.K. Jansen | ACPI4 | Asteraceae | |
| hairy suncup | Camissonia pubens (S. Wats.) Raven | CAPU15 | Onagraceae | |
| hairy torchwood | Amyris diatrypa Spreng. | AMDI4 | Rutaceae | |
| hairy whitetop | Cardaria pubescens (C.A. Mey.) Jarmolenko | CAPU6 | Brassicaceae | |
| hairy wild cabbage | Caulanthus pilosus S. Wats. | CAPI4 | Brassicaceae | |
| hairy woodland brome | Bromus pubescens Muhl. ex Willd. | BRPU6 | Poaceae | |
| hairyflower bellflower | Campanula chamissonis Fedorov | CACH | Campanulaceae | |
| hairyfruit chervil | Chaerophyllum tainturieri Hook. | CHTA | Apiaceae | |
| hairyfruit chervil | Chaerophyllum tainturieri Hook. var. dasycarpum Hook. ex S. Wats. | CHTAD | Apiaceae | |
| hairyfruit chervil | Chaerophyllum tainturieri Hook. var. tainturieri | CHTAT | Apiaceae | |
| hairyfruit sedge | Carex trichocarpa Muhl. ex Willd. | CATR8 | Cyperaceae | |
| hairy-pod milkvetch | Astragalus concordius Welsh | ASCO61 | Fabaceae | |
| hairyseed bahia | Bahia absinthifolia Benth. | BAAB | Asteraceae | |
| hairyseed bahia | Bahia absinthifolia Benth. var. absinthifolia | BAABA | Asteraceae | |
| hairystem rockcress | Arabis sparsiflora Nutt. var. subvillosa (S. Wats.) Rollins | ARSPS | Brassicaceae | |
| Haitian catalpa | Catalpa longissima (Jacq.) Dum.-Cours. | CALO8 | Bignoniaceae | |
| halberdleaf orach | Atriplex calotheca (Rafn) Fr. | ATCA6 | Chenopodiaceae | |
| Haleakala clermontia | Clermontia tuberculata Forbes | CLTU2 | Campanulaceae | |
| Haleakala cyanea | Cyanea aculeatiflora Rock | CYAC4 | Campanulaceae | |
| Haleakala spleenwort | Asplenium haleakalense W.H. Wagner | ASHA14 | Aspleniaceae | |
| halfmoon milkvetch | Astragalus allochrous Gray | ASAL6 | Fabaceae | |
| halfmoon milkvetch | Astragalus allochrous Gray var. allochrous | ASALA10 | Fabaceae | |
| halfmoon milkvetch | Astragalus allochrous Gray var. playanus Isely | ASALP | Fabaceae | |
| Haller's bartramia moss | Bartramia halleriana Hedw. | BAHA4 | Bartramiaceae | |
| Haller's campylium moss | Campylium halleri (Hedw.) Lindb. | CAHA33 | Amblystegiaceae | |
| Hall's archidium moss | Archidium hallii Aust. | ARHA9 | Archidiaceae | |
| Hall's arthothelium lichen | Arthothelium hallii (Tuck.) Zahlbr. | ARHA7 | Uncertain Lichen Family | |
| Hall's bentgrass | Agrostis hallii Vasey | AGHA2 | Poaceae | |
| Hall's bruchia moss | Bruchia hallii Aust. | BRHA2 | Bruchiaceae | |
| Hall's columbiadoria | Columbiadoria hallii (Gray) Nesom | COHA5 | Asteraceae | |
| Hall's hawksbeard | Crepis runcinata (James) Torr. & Gray ssp. hallii Babcock & Stebbins | CRRUH | Asteraceae | |
| Hall's milkvetch | Astragalus hallii Gray | ASHA2 | Fabaceae | |
| Hall's milkvetch | Astragalus hallii Gray var. fallax (M.E. Jones) Barneby | ASHAF | Fabaceae | |
| Hall's milkvetch | Astragalus hallii Gray var. hallii | ASHAH | Fabaceae | |
| Hall's milkweed | Asclepias hallii Gray | ASHA6 | Asclepiadaceae | |
| Hall's mule-ears | Agnorhiza elata (Hall) W.A. Weber | AGEL8 | Asteraceae | |
| Hall's sedge | Carex halliana Bailey | CAHA2 | Cyperaceae | |
| Hall's suncup | Camissonia pallida (Abrams) Raven ssp. hallii (A. Davids.) Raven | CAPAH2 | Onagraceae | |
| Hall's wild cabbage | Caulanthus hallii Payson | CAHA8 | Brassicaceae | |
| Hamakua clermontia | Clermontia pyrularia Hbd. | CLPY2 | Campanulaceae | |
| hame | Antidesma pulvinatum Hbd. | ANPU2 | Euphorbiaceae | |
| Hamilton's milkvetch | Astragalus hamiltonii C.L. Porter | ASHA3 | Fabaceae | |
| hammer sedge | Carex hirta L. | CAHI10 | Cyperaceae | |
| hammock fern | Blechnum occidentale L. | BLOC | Blechnaceae | |
| hammock sedge | Carex fissa Mackenzie | CAFI5 | Cyperaceae | |
| hammock sedge | Carex fissa Mackenzie var. aristata F.J. Herm. | CAFIA | Cyperaceae | |
| hammock sedge | Carex fissa Mackenzie var. fissa | CAFIF | Cyperaceae | |
| hammock snakeroot | Ageratina jucunda (Greene) Clewell & Woot. | AGJU2 | Asteraceae | |
| Hammond's claytonia | Claytonia virginica L. var. hammondiae (Kalmbacher) Doyle, Lewis & Snyder | CLVIH | Portulacaceae | |
| Hana clermontia | Clermontia samuelii Forbes | CLSA5 | Campanulaceae | |
| Hana clermontia | Clermontia samuelii Forbes ssp. hanaensis (St. John) Lammers | CLSAH2 | Campanulaceae | |
| Hana clermontia | Clermontia samuelii Forbes ssp. samuelii | CLSAS | Campanulaceae | |
| Hana Forest silversword | Argyroxiphium grayanum (Hbd.) O. Deg. | ARGR5 | Asteraceae | |
| hand fern | Cheiroglossa palmata (L.) K. Presl | CHPA14 | Ophioglossaceae | |
| handsome cryptantha | Cryptantha paradoxa (A. Nels.) Payson | CRPA6 | Boraginaceae | |
| handsome sedge | Carex formosa Dewey | CAFO4 | Cyperaceae | |
| hanging sedge | Carex pendula Huds. | CAPE45 | Cyperaceae | |
| hangingpod milkvetch | Astragalus atropubescens Coult. & Fisher | ASAT2 | Fabaceae | |
| Hansen's bird's beak | Cordylanthus pilosus Gray ssp. hansenii (Ferris) Chuang & Heckard | COPIH | Scrophulariaceae | |
| hapu'u | Cibotium glaucum (Sm.) Hook. & Arn. | CIGL | Dicksoniaceae | |
| hapu'u li | Cibotium menziesii Hook. | CIME8 | Dicksoniaceae | |
| Harbison's hawthorn | Crataegus harbisonii Beadle | CRHA2 | Rosaceae | |
| Hardham's evening-primrose | Camissonia hardhamiae Raven | CAHA15 | Onagraceae | |
| hardheads | Acroptilon Cass. | ACROP | Asteraceae | |
| hardheads | Acroptilon repens (L.) DC. | ACRE3 | Asteraceae | |
| hardy swamplily | Crinum bulbispermum (Burm. f.) Milne-Redhead & Schweickerdt | CRBU2 | Liliaceae | |
| harebell | Asyneuma Griseb. & Schenk | ASYNE | Campanulaceae | |
| hare's ear | Bupleurum rotundifolium L. | BURO | Apiaceae | |
| hare's ear mustard | Conringia Heister ex Fabr. | CONRI | Brassicaceae | |
| hare's ear mustard | Conringia orientalis (L.) Dumort. | COOR | Brassicaceae | |
| Harford's sedge | Carex harfordii Mackenzie | CAHA4 | Cyperaceae | |
| harlequin dutchman's pipe | Aristolochia anguicida Jacq. | ARAN6 | Aristolochiaceae | |
| harlequin glorybower | Clerodendrum trichotomum Thunb. | CLTR | Verbenaceae | |
| Harold's milkvetch | Astragalus robbinsii (Oakes) Gray var. harringtonii (Rydb.) Barneby | ASROH | Fabaceae | |
| Harper's dodder | Cuscuta harperi Small | CUHA | Cuscutaceae | |
| Harper's searocket | Cakile edentula (Bigelow) Hook. ssp. harperi (Small) Rodman | CAEDH | Brassicaceae | |
| Harper's sedge | Carex leptalea Wahlenb. ssp. harperi (Fern.) W. Stone | CALEH | Cyperaceae | |
| Harrington's cephalotaxus | Cephalotaxus harringtonia (Knight ex Forbes) K. Koch | CEHA2 | Cephalotaxaceae | |
| Harris' dwarf sand verbena | Abronia nana S. Wats. var. harrisii Welsh | ABNAH | Nyctaginaceae | |
| Harrison's barberry | Berberis harrisoniana Kearney & Peebles | BEHA2 | Berberidaceae | |
| Harrison's milkvetch | Astragalus harrisonii Barneby | ASHA4 | Fabaceae | |
| harsh cyanea | Cyanea scabra Hbd. | CYSC7 | Campanulaceae | |
| harsh Indian paintbrush | Castilleja hispida Benth. | CAHI9 | Scrophulariaceae | |
| harsh Indian paintbrush | Castilleja hispida Benth. ssp. hispida | CAHIH2 | Scrophulariaceae | |
| Hart's tonguefern | Asplenium scolopendrium L. | ASSC11 | Aspleniaceae | |
| Hart's tonguefern | Asplenium scolopendrium L. var. americanum (Fern.) Kartesz & Gandhi | ASSCA | Aspleniaceae | |
| Hartweg's cyphomandra | Cyphomandra hartwegii (Miers) Dunal | CYHA12 | Solanaceae | |
| Hartweg's milkvetch | Astragalus hartwegii Benth. | ASHA5 | Fabaceae | |
| Hartweg's spineflower | Chorizanthe pungens Benth. var. hartwegiana Reveal & Hardham | CHPUH2 | Polygonaceae | |
| Hartweg's sundrops | Calylophus hartwegii (Benth.) Raven | CAHA14 | Onagraceae | |
| Hartweg's sundrops | Calylophus hartwegii (Benth.) Raven ssp. fendleri (Gray) Towner & Raven | CAHAF | Onagraceae | |
| Hartweg's sundrops | Calylophus hartwegii (Benth.) Raven ssp. filifolius (Eastw.) Towner & Raven | CAHAF2 | Onagraceae | |
| Hartweg's sundrops | Calylophus hartwegii (Benth.) Raven ssp. hartwegii | CAHAH | Onagraceae | |
| Hartweg's sundrops | Calylophus hartwegii (Benth.) Raven ssp. pubescens (Gray) Towner & Raven | CAHAP | Onagraceae | |
| Hartweg's wildginger | Asarum hartwegii S. Wats. | ASHA | Aristolochiaceae | |
| harvest brodiaea | Brodiaea elegans Hoover | BREL | Liliaceae | |
| harvest brodiaea | Brodiaea elegans Hoover ssp. elegans | BRELE | Liliaceae | |
| harvestlice | Agrimonia parviflora Ait. | AGPA6 | Rosaceae | |
| Harvey's hawthorn | Crataegus harveyana Sarg. | CRHA4 | Rosaceae | |
| Harwood's milkvetch | Astragalus insularis Kellogg var. harwoodii Munz & McBurney | ASINH | Fabaceae | |
| haspan flatsedge | Cyperus haspan L. | CYHA | Cyperaceae | |
| Hasse's cracked lichen | Acarospora hassei Herre | ACHA3 | Acarosporaceae | |
| Hassler's alternanthera | Alternanthera hassleriana Chodat ex Chodat & Hassler | ALHA3 | Amaranthaceae | |
| Haussknecht's atrichum moss | Atrichum haussknechtii Jur. & Milde | ATHA4 | Polytrichaceae | |
| Havana snakeroot | Ageratina havanensis (Kunth) King & H.E. Robins. | AGHA4 | Asteraceae | |
| Havard's century plant | Agave havardiana Trel. | AGHA | Agavaceae | |
| Havard's false willow | Baccharis havardii Gray | BAHA2 | Asteraceae | |
| Havard's threeawn | Aristida havardii Vasey | ARHA3 | Poaceae | |
| Hawai'i alectryon | Alectryon macrococcus Radlk. | ALMA | Sapindaceae | |
| Hawai'i alectryon | Alectryon macrococcus Radlk. var. auwahiensis G. Linney | ALMAA | Sapindaceae | |
| Hawai'i alectryon | Alectryon macrococcus Radlk. var. macrococcus | ALMAM2 | Sapindaceae | |
| Hawai'i beggarticks | Bidens hawaiensis Gray | BIHA | Asteraceae | |
| Hawai'i bentgrass | Agrostis sandwicensis Hbd. | AGSA3 | Poaceae | |
| Hawai'I birdnest fern | Asplenium nidus L. | ASNI | Aspleniaceae | |
| Hawai'i chaff flower | Achyranthes atollensis St. John | ACAT | Amaranthaceae | |
| Hawai'i cyrtandra | Cyrtandra hawaiensis C.B. Clarke | CYHA4 | Gesneriaceae | |
| Hawai'i dogweed | Bobea sandwicensis (Gray) Hbd. | BOSA2 | Rubiaceae | |
| Hawai'i false nettle | Boehmeria grandis (Hook. & Arn.) Heller | BOGR3 | Urticaceae | |
| Hawai'i jeweled orchid | Anoectochilus sandvicensis Lindl. | ANSA2 | Orchidaceae | |
| Hawai'i kauilatree | Alphitonia ponderosa Hbd. | ALPO3 | Rhamnaceae | |
| Hawai'i lady's nightcap | Bonamia menziesii Gray | BOME2 | Convolvulaceae | |
| Hawai'I lopleaf | Cypholophus moluccanus (Blume) Miq. | CYMO12 | Urticaceae | |
| Hawai'i mirrorplant | Coprosma cymosa Hbd. | COCY3 | Rubiaceae | |
| Hawai'i pearls | Caesalpinia major (Medik.) Dandy & Exell | CAMA21 | Fabaceae | |
| Hawai'i sedge | Carex alligata Boott | CAAL12 | Cyperaceae | |
| Hawai'i silversword | Argyroxiphium sandwicense DC. | ARSA5 | Asteraceae | |
| Hawai'i silversword | Argyroxiphium sandwicense DC. ssp. macrocephalum (Gray) Mérat | ARSAM | Asteraceae | |
| Hawai'i silversword | Argyroxiphium sandwicense DC. ssp. sandwicense | ARSAS | Asteraceae | |
| hawksbeard | Crepis L. | CREPI | Asteraceae | |
| Haworth's aeonium | Aeonium haworthii Webb & Berth. | AEHA2 | Crassulaceae | |
| hawthorn | Crataegus L. | CRATA | Rosaceae | |
| hawthorn | Crataegus paludosa Sarg. | CRPA24 | Rosaceae | |
| hay sedge | Carex argyrantha Tuckerman | CAAR4 | Cyperaceae | |
| Hayden's Indian paintbrush | Castilleja haydenii (Gray) Cockerell | CAHA16 | Scrophulariaceae | |
| Hayden's milkvetch | Astragalus bisulcatus (Hook.) Gray var. haydenianus (Gray) Barneby | ASBIH | Fabaceae | |
| Hayden's sedge | Carex haydenii Dewey | CAHA7 | Cyperaceae | |
| hazel alder | Alnus serrulata (Ait.) Willd. | ALSE2 | Betulaceae | |
| hazel dodder | Cuscuta coryli Engelm. | CUCO3 | Cuscutaceae | |
| hazelnut | Corylus L. | CORYL | Betulaceae | |
| head sandmat | Chamaesyce capitellata (Engelm.) Millsp. | CHCA29 | Euphorbiaceae | |
| headachevine | Clematis microphylla DC. | CLMI8 | Ranunculaceae | |
| heal and draw | Chaptalia nutans (L.) Polak. | CHNU2 | Asteraceae | |
| healing croton | Croton argyranthemus Michx. | CRAR2 | Euphorbiaceae | |
| Hearst Ranch buckbrush | Ceanothus hearstiorum Hoover & J.B. Roof | CEHE2 | Rhamnaceae | |
| Hearst's manzanita | Arctostaphylos hookeri G. Don ssp. hearstiorum (Hoover & J.B. Roof) P.V. Wells | ARHOH | Ericaceae | |
| heart of Jesus | Caladium bicolor (Ait.) Vent. | CABI11 | Araceae | |
| heartleaf arnica | Arnica cordifolia Hook. | ARCO9 | Asteraceae | |
| heartleaf bittercress | Cardamine cordifolia Gray | CACO6 | Brassicaceae | |
| heartleaf bittercress | Cardamine cordifolia Gray var. cordifolia | CACOC | Brassicaceae | |
| heartleaf bittercress | Cardamine cordifolia Gray var. incana Gray ex M.E. Jones | CACOI | Brassicaceae | |
| heartleaf bittercress | Cardamine cordifolia Gray var. lyallii (S. Wats.) A. Nels. & J.F. Macbr. | CACOL4 | Brassicaceae | |
| heartleaf cyrtandra | Cyrtandra cordifolia Gaud. | CYCO9 | Gesneriaceae | |
| heartleaf iceplant | Aptenia cordifolia (L. f.) Schwant. | APCO | Aizoaceae | |
| heartleaf madeiravine | Anredera cordifolia (Ten.) Steenis | ANCO6 | Basellaceae | |
| heartleaf milkweed | Asclepias cordifolia (Benth.) Jepson | ASCO | Asclepiadaceae | |
| heartleaf peppervine | Ampelopsis cordata Michx. | AMCO2 | Vitaceae | |
| heartleaf sandmat | Chamaesyce cordifolia (Ell.) Small | CHCO11 | Euphorbiaceae | |
| heartleaf springbeauty | Claytonia cordifolia S. Wats. | CLCO3 | Portulacaceae | |
| heartleaf suncup | Camissonia cardiophylla (Torr.) Raven | CACA34 | Onagraceae | |
| heartleaf suncup | Camissonia cardiophylla (Torr.) Raven ssp. cardiophylla | CACAC9 | Onagraceae | |
| heartleaf suncup | Camissonia cardiophylla (Torr.) Raven ssp. robusta (Raven) Raven | CACAR2 | Onagraceae | |
| heartleaf thorn-mint | Acanthomintha obovata Jepson ssp. cordata Jokerst | ACOBC | Lamiaceae | |
| hearts entangled | Ceropegia woodii Schltr. | CEWO | Asclepiadaceae | |
| heartscale | Atriplex cordulata Jepson | ATCO2 | Chenopodiaceae | |
| heartseed | Cardiospermum microcarpum Kunth | CAMI21 | Sapindaceae | |
| heath false brome | Brachypodium pinnatum (L.) Beauv. | BRPI | Poaceae | |
| heath sedge | Carex flacca Schreb. | CAFL8 | Cyperaceae | |
| heath wrightwort | Carlowrightia linearifolia (Torr.) Gray | CALI2 | Acanthaceae | |
| heather | Calluna Salisb. | CALLU | Ericaceae | |
| heather | Calluna vulgaris (L.) Hull | CAVU | Ericaceae | |
| heath-leaf banksia | Banksia ericifolia L. f. | BAER | Proteaceae | |
| heatloving cracked lichen | Acarospora thermophila Herre | ACTH6 | Acarosporaceae | |
| heavy sedge | Carex gravida Bailey | CAGR4 | Cyperaceae | |
| heavy sedge | Carex gravida Bailey var. gravida | CAGRG2 | Cyperaceae | |
| heavy sedge | Carex gravida Bailey var. lunelliana (Mackenzie) F.J. Herm. | CAGRL | Cyperaceae | |
| Heckard's Indian paintbrush | Castilleja montigena Heckard | CAMO20 | Scrophulariaceae | |
| hedge bamboo | Bambusa multiplex (Lour.) Raeusch. ex J.A. & J.H. Schultes | BAMU2 | Poaceae | |
| hedge cactus | Cereus hildmannianus K. Schum. | CEHI3 | Cactaceae | |
| hedge false bindweed | Calystegia sepium (L.) R. Br. | CASE13 | Convolvulaceae | |
| hedge false bindweed | Calystegia sepium (L.) R. Br. ssp. americana (Sims) Brummitt | CASEA2 | Convolvulaceae | |
| hedge false bindweed | Calystegia sepium (L.) R. Br. ssp. angulata Brummitt | CASEA3 | Convolvulaceae | |
| hedge false bindweed | Calystegia sepium (L.) R. Br. ssp. erratica Brummitt | CASEE | Convolvulaceae | |
| hedge false bindweed | Calystegia sepium (L.) R. Br. ssp. limnophila (Greene) Brummitt | CASEL | Convolvulaceae | |
| hedge false bindweed | Calystegia sepium (L.) R. Br. ssp. sepium | CASES | Convolvulaceae | |
| hedge maple | Acer campestre L. | ACCA5 | Aceraceae | |
| hedgehog gourd | Cucumis dipsaceus C.G. Ehrenb. ex Spach | CUDI2 | Cucurbitaceae | |
| hedgehog pricklypoppy | Argemone squarrosa Greene | ARSQ | Papaveraceae | |
| hedgehog pricklypoppy | Argemone squarrosa Greene ssp. glabrata G.B. Ownbey | ARSQG | Papaveraceae | |
| hedgehog pricklypoppy | Argemone squarrosa Greene ssp. squarrosa | ARSQS | Papaveraceae | |
| Heimburger's anemone | Anemone drummondii S. Wats. ssp. heimburgeri A.& D. Löve | ANDRH | Ranunculaceae | |
| Heinemann's andreaea moss | Andreaea heinemannii Hampe & C. Müll. | ANHE10 | Andreaeaceae | |
| helecho gigante | Cyathea tenera (J. Sm. ex Hook.) T. Moore | CYTE10 | Cyatheaceae | |
| helecho gigante de la sierra | Alsophila bryophila R. Tryon | ALBR4 | Cyatheaceae | |
| Heller's bird's-beak | Cordylanthus kingii S. Wats. ssp. helleri (Ferris) Chuang & Heckard | COKIH | Scrophulariaceae | |
| Heller's sedge | Carex helleri Mackenzie | CAHE6 | Cyperaceae | |
| helmet orchid | Cranichis Sw. | CRANI | Orchidaceae | |
| hemlock dwarf mistletoe | Arceuthobium tsugense (Rosendahl) G.N. Jones | ARTS | Viscaceae | |
| hemlock dwarf mistletoe | Arceuthobium tsugense (Rosendahl) G.N. Jones ssp. mertensianae Hawksworth & Nickrent | ARTSM2 | Viscaceae | |
| hemlock dwarf mistletoe | Arceuthobium tsugense (Rosendahl) G.N. Jones ssp. tsugense | ARTST2 | Viscaceae | |
| hemlockparsley | Conioselinum Hoffmann | CONIO | Apiaceae | |
| hemp | Cannabis L. | CANNA | Cannabaceae | |
| Henderson's angelica | Angelica hendersonii Coult. & Rose | ANHE | Apiaceae | |
| Henderson's bentgrass | Agrostis hendersonii A.S. Hitchc. | AGHE3 | Poaceae | |
| Henderson's milkvetch | Astragalus accidens S. Wats. var. hendersonii M.E. Jones | ASACH | Fabaceae | |
| Henderson's needlegrass | Achnatherum hendersonii (Vasey) Barkworth | ACHE10 | Poaceae | |
| Henderson's sedge | Carex hendersonii Bailey | CAHE7 | Cyperaceae | |
| henequen | Agave fourcroydes Lemaire | AGFO2 | Agavaceae | |
| Henry Indian paintbrush | Castilleja parviflora Bong. var. oreopola (Greenm.) Ownbey | CAPAO | Scrophulariaceae | |
| hen's eyes | Ardisia crenata Sims | ARCR80 | Myrsinaceae | |
| Henson's calammophila | ×Calammophila don-hensonii Reznicek & E.J. Judziewicz [Ammophila breviligulata × Calamagrostis canadensis] | CADO7 | Poaceae | |
| Hepburn's sedge | Carex nardina Fries var. hepburnii (Boott) Kükenth. | CANAH | Cyperaceae | |
| Hepp's cracked lichen | Acarospora heppii (Nageli ex Hepp) Nageli ex Korber | ACHE6 | Acarosporaceae | |
| herb of Gilead | Cedronella canariensis (L.) Willd. ex Webb & Berth. | CECA | Lamiaceae | |
| herb of grace | Bacopa monnieri (L.) Pennell | BAMO | Scrophulariaceae | |
| herbert river cherry | Antidesma dallachyanum Baillon | ANDA2 | Euphorbiaceae | |
| Herbst's sandmat | Chamaesyce herbstii W.L. Wagner | CHHE3 | Euphorbiaceae | |
| Herbst's sedge | Carex wahuensis C.A. Mey. ssp. herbstii T. Koyama | CAWAH | Cyperaceae | |
| hermaphrodite flatsedge | Cyperus hermaphroditus (Jacq.) Standl. | CYHE2 | Cyperaceae | |
| hermit milkvetch | Astragalus eremiticus Sheldon | ASER4 | Fabaceae | |
| Hesse's pussypaws | Cistanthe parryi (Gray) Hershkovitz var. hesseae (Thomas) Kartesz & Gandhi | CIPAH | Portulacaceae | |
| Heufler's cracked lichen | Acarospora heufleriana Korber | ACHE7 | Acarosporaceae | |
| hians goosefoot | Chenopodium hians Standl. | CHHI | Chenopodiaceae | |
| Hickman's onion | Allium hickmanii Eastw. | ALHI | Liliaceae | |
| hickory | Carya Nutt. | CARYA | Juglandaceae | |
| hiddenpetal Indian mallow | Abutilon eremitopetalum Caum | ABER | Malvaceae | |
| Higgins' milkvetch | Astragalus lentiginosus Dougl. ex Hook. var. higginsii Welsh & Thorne | ASLEH | Fabaceae | |
| Higgins' springparsley | Cymopterus acaulis (Pursh) Raf. var. higginsii (Welsh) Goodrich | CYACH | Apiaceae | |
| higuerito | Crescentia linearifolia Miers | CRLI5 | Bignoniaceae | |
| higuero de sierra | Crescentia portoricensis Britt. | CRPO6 | Bignoniaceae | |
| Hilgard's suncup | Camissonia hilgardii (Greene) Raven | CAHI12 | Onagraceae | |
| Hill Country silverbush | Argythamnia aphoroides Muell.-Arg. | ARAP | Euphorbiaceae | |
| hill suncup | Camissonia graciliflora (Hook. & Arn.) Raven | CAGR14 | Onagraceae | |
| Hillebrand's flatsedge | Cyperus hillebrandii Boeckl. | CYHI | Cyperaceae | |
| Hillebrand's flatsedge | Cyperus hillebrandii Boeckl. var. decipiens (Hbd.) Kükenth. | CYHID | Cyperaceae | |
| Hillebrand's flatsedge | Cyperus hillebrandii Boeckl. var. hillebrandii | CYHIH2 | Cyperaceae | |
| Hillebrand's ha'a | Antidesma platyphyllum Mann var. hillebrandii Pax & K. Hoffmann | ANPLH2 | Euphorbiaceae | |
| Hillegrand's reedgrass | Calamagrostis hillebrandii (Munro ex Hbd.) A.S. Hitchc. | CAHI | Poaceae | |
| Hillman's silverscale | Atriplex hillmanii (M.E. Jones) Standley | ATHI | Chenopodiaceae | |
| Hillman's stinkweed | Cleomella hillmanii A. Nels. | CLHI2 | Capparaceae | |
| Hill's thistle | Cirsium hillii (Canby) Fern. | CIHI | Asteraceae | |
| hillside clermontia | Clermontia lindseyana Rock | CLLI3 | Campanulaceae | |
| hillside false bindweed | Calystegia subacaulis Hook. & Arn. | CASU19 | Convolvulaceae | |
| hillside false bindweed | Calystegia subacaulis Hook. & Arn. ssp. episcopalis Brummitt | CASUE | Convolvulaceae | |
| hillside false bindweed | Calystegia subacaulis Hook. & Arn. ssp. subacaulis | CASUS2 | Convolvulaceae | |
| hillside milkvetch | Astragalus collinus (Hook.) Dougl. ex G. Don | ASCO7 | Fabaceae | |
| hillside milkvetch | Astragalus collinus (Hook.) Dougl. ex G. Don var. collinus | ASCOC7 | Fabaceae | |
| hilly sandwort | Arenaria benthamii Fenzl ex Torr. & Gray | ARBE | Caryophyllaceae | |
| hillyhock | Callaeum ?macropterum (DC.) D.M. Johnson | CAMA45 | Malpighiaceae | |
| Himalayan cypress | Cupressus torulosa D. Don | CUTO2 | Cupressaceae | |
| Himalayan foothill borinda | Borinda fungosa (T.P. Yi) C.M.A. Stapleton | BOFU | Poaceae | |
| Himalayan hazelnut | Corylus ferox Wallich | COFE5 | Betulaceae | |
| Himalayan hazelnut | Corylus ferox Wallich var. ferox | COFEF | Betulaceae | |
| Hinckley's brickellbush |