| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| HULUN | Humulus lupulus L. var. neomexicanus A. Nels. & Cockerell | common hop | Cannabaceae
|
| HULUP | Humulus lupulus L. var. pubescens E. Small | common hop | Cannabaceae
|
| HULU | Humulus lupulus L. | common hop | Cannabaceae
|
| HUSC | Humulus scandens auct. non (Lour.) Merr. | Humulus japonicus | Cannabaceae
|
| HUMUL | Humulus L. | hop | Cannabaceae
|
| HUFU | Hunnemannia fumariifolia Sweet | Mexican tulip poppy | Papaveraceae
|
| HUNNE | Hunnemannia Sweet | hunnemannia | Papaveraceae
|
| HUTE2 | Hunzikeria texana (Torr.) D'Arcy | Texas cupflower | Solanaceae
|
| HUNZI | Hunzikeria D'Arcy | hunzikeria | Solanaceae
|
| HUAC | Huperzia acerosa (Sw.) Holub | Puerto Rico clubmoss | Lycopodiaceae
|
| HUAP | Huperzia appalachiana Beitel & Mickel | Appalachian clubmoss | Lycopodiaceae
|
| HUAQ | Huperzia aqualupiana (Spring) Rothm. | treetrunk clubmoss | Lycopodiaceae
|
| HUBA | Huperzia �bartleyi (Cusick) Kartesz & Gandhi | | Lycopodiaceae
|
| HUBU | Huperzia �buttersii (Abbe) Kartesz & Gandhi | | Lycopodiaceae
|
| HUCH | Huperzia chinensis (Christ) Czern. | Chinese clubmoss | Lycopodiaceae
|
| HUDI | Huperzia dichotoma (Jacq.) Trevisan | hanging clubmoss | Lycopodiaceae
|
| HUER2 | Huperzia �erubescens (Brack.) Holub | | Lycopodiaceae
|
| HUFI | Huperzia filiformis (Sw.) Holub | stringleaf clubmoss | Lycopodiaceae
|
| HUFU2 | Huperzia funiformis (Cham. ex Spring) Trevisan | royal clubmoss | Lycopodiaceae
|
| HUHA | Huperzia haleakalae (Brack.) Holub | Pacific clubmoss | Lycopodiaceae
|
| HUHE2 | Huperzia �helleri (Herter) Kartesz & Gandhi | | Lycopodiaceae
|
| HULI | Huperzia linifolia (L.) Trevisan | needleleaf clubmoss | Lycopodiaceae
|
| HULU2 | Huperzia lucidula (Michx.) Trevisan | shining clubmoss | Lycopodiaceae
|
| HUMA | Huperzia mannii (Hbd.) Kartesz & Gandhi | Mann's clubmoss | Lycopodiaceae
|
| HUMI | Huperzia miyoshiana (Makino) Ching | Huperzia chinensis | Lycopodiaceae
|
| HUNU | Huperzia nutans (Brack.) Rothm. | nodding clubmoss | Lycopodiaceae
|
| HUOC | Huperzia occidentalis (Clute) Kartesz & Gandhi | western clubmoss | Lycopodiaceae
|
| HUPH | Huperzia phyllantha (Hook. & Arn.) Holub | daggerleaf clubmoss | Lycopodiaceae
|
| HUPO | Huperzia polytrichoides (Kaulfuss) Trevisan | treelimb clubmoss | Lycopodiaceae
|
| HUPO2 | Huperzia porophila (Lloyd & Underwood) Holub | rock clubmoss | Lycopodiaceae
|
| HURE | Huperzia reflexa (Lam.) Trevisan | Antilles clubmoss | Lycopodiaceae
|
| HUSEA | Huperzia selago (L.) Bernh. ssp. arctica (Grossh.) A.& D. L�ve | Huperzia selago var. densa | Lycopodiaceae
|
| HUSEC | Huperzia selago (L.) Bernh. ssp. chinensis (Christ) A.& D. L�ve | Huperzia chinensis | Lycopodiaceae
|
| HUSEL | Huperzia selago (L.) Bernh. ssp. lucidula (Michx.) A.& D. L�ve | Huperzia lucidula | Lycopodiaceae
|
| HUSES3 | Huperzia selago (L.) Bernh. ssp. serrata (Thunb. ex Murr.) A.& D. L�ve | Huperzia serrata var. serrata | Lycopodiaceae
|
| HUSED | Huperzia selago (L.) Bernh. ex Mart. & Schrank var. densa Trevisan | fir clubmoss | Lycopodiaceae
|
| HUSEM | Huperzia selago (L.) Bernh. var. miyoshiana (Makino) Taylor & MacBryde | Huperzia chinensis | Lycopodiaceae
|
| HUSEP2 | Huperzia selago (L.) Bernh. var. patens (Beauv.) Trevisan | Huperzia porophila | Lycopodiaceae
|
| HUSEP | Huperzia selago (L.) Bernh. var. porophila (Lloyd & Underwood) A.& D. L�ve | Huperzia porophila | Lycopodiaceae
|
| HUSES | Huperzia selago (L.) Bernh. ex Mart. & Schrank var. selago | fir clubmoss | Lycopodiaceae
|
| HUSE | Huperzia selago (L.) Bernh. | fir clubmoss | Lycopodiaceae
|
| HUSED2 | Huperzia serrata (Thunb. ex Murr.) Trevisan var. dentata (Hbd.) Kartesz & Gandhi | toothed clubmoss | Lycopodiaceae
|
| HUSES2 | Huperzia serrata (Thunb. ex Murr.) Trevisan var. serrata | toothed clubmoss | Lycopodiaceae
|
| HUSE2 | Huperzia serrata (Thunb. ex Murr.) Trevisan | toothed clubmoss | Lycopodiaceae
|
| HUSI | Huperzia sintenisii (Herter) Holub | Sintenis' clubmoss | Lycopodiaceae
|
| HUST | Huperzia stemmermanniae (A.C. Medeiros & W.H. Wagner) Kartesz, comb. nov. ined. | Stemmermann's' clubmoss | Lycopodiaceae
|
| HUSU | Huperzia sulcinervia (Spring) Trevisan | monarch clubmoss | Lycopodiaceae
|
| HUTA | Huperzia taxifolia (Sw.) Trevisan | yewleaf clubmoss | Lycopodiaceae
|
| HUTE | Huperzia tenuicaulis (Underwood & Lloyd) B. Pllg. | narrowleaf clubmoss | Lycopodiaceae
|
| HUVE2 | Huperzia verticillata auct. non (L. f.) Trevisan | Huperzia acerosa | Lycopodiaceae
|
| HUWI | Huperzia wilsonii (Underwood & Lloyd) B. Pllg. | Wilson's clubmoss | Lycopodiaceae
|
| HUPER | Huperzia Bernh. | clubmoss | Lycopodiaceae
|
| HUCR | Hura crepitans L. | sandbox tree | Euphorbiaceae
|
| HURA | Hura L. | sandbox tree | Euphorbiaceae
|
| HUPR2 | Husnotiella pringlei (Card.) Grout | Didymodon tophaceus | Pottiaceae
|
| HUREP | Husnotiella revoluta Card. var. palmeri (Card.) Bartr. | Didymodon revolutus | Pottiaceae
|
| HURE2 | Husnotiella revoluta Card. | Didymodon revolutus | Pottiaceae
|
| HUTO2 | Husnotiella torquescens (Card.) Bartr. | Trichostomopsis australasiae | Pottiaceae
|
| HUCAA | Hutchinsia calycina Steph. ex Willd. var. americana Regel & Herder | Smelowskia calycina var. americana | Brassicaceae
|
| HUCAI | Hutchinsia calycina Steph. ex Willd. var. integrifolia Seem. | Smelowskia calycina var. integrifolia | Brassicaceae
|
| HUPR | Hutchinsia procumbens (L.) Desv. | prostrate hutchinsia | Brassicaceae
|
| HUTCH | Hutchinsia Ait. f. | hutchinsia | Brassicaceae
|
| HUCH2 | Hutera cheiranthos (Vill.) Gomez-Campo | Coincya monensis ssp. recurvata | Brassicaceae
|
| HYHI5 | Hyacinthoides hispanica (P. Mill.) Rothm. | Hispanic hyacinthoides | Liliaceae
|
| HYNO | Hyacinthoides nonscripta (L.) Chouard ex Rothm. | English bluebell | Liliaceae
|
| HYACI | Hyacinthoides Medik. | hyacinthoides | Liliaceae
|
| HYBO5 | Hyacinthus botryoides L. | Muscari botryoides | Liliaceae
|
| HYOR | Hyacinthus orientalis L. | garden hyacinth | Liliaceae
|
| HYACI2 | Hyacinthus L. | hyacinth | Liliaceae
|
| HYAT | Hybanthus attenuatus (Humb. & Bonpl. ex J.A. Schultes) G.K. Schulze | western greenviolet | Violaceae
|
| HYCO6 | Hybanthus concolor (T.F. Forst.) Spreng. | eastern greenviolet | Violaceae
|
| HYLI3 | Hybanthus linearifolius (Vahl) Urban | chancleta | Violaceae
|
| HYLI6 | Hybanthus linearis (Torr.) Shinners | Hybanthus verticillatus var. verticillatus | Violaceae
|
| HYPO2 | Hybanthus portoricensis Urban | Hybanthus linearifolius | Violaceae
|
| HYVEP | Hybanthus verticillatus (Ortega) Baill. var. platyphyllus (Gray) Cory & Parks | babyslippers | Violaceae
|
| HYVEV2 | Hybanthus verticillatus (Ortega) Baill. var. verticillatus | babyslippers | Violaceae
|
| HYVE | Hybanthus verticillatus (Ortega) Baill. | babyslippers | Violaceae
|
| HYBAN | Hybanthus Jacq. | greenviolet | Violaceae
|
| HYSP7 | Hybosperma spinosum Urban | Colubrina verrucosa | Rhamnaceae
|
| HYBO4 | Hydastylus borealis Bickn. | Sisyrinchium californicum | Iridaceae
|
| HYBR8 | Hydastylus brachypus Bickn. | Sisyrinchium californicum | Iridaceae
|
| HYCA15 | Hydastylus californicus (Ker-Gawl. ex Sims) Salisb. | Sisyrinchium californicum | Iridaceae
|
| HYEL4 | Hydastylus elmeri (Greene) Bickn. | Sisyrinchium elmeri | Iridaceae
|
| HYFO2 | Hydatica foliolosa (R. Br.) Small | Saxifraga foliolosa | Saxifragaceae
|
| HYPE7 | Hydatica petiolaris (Raf.) Small | Saxifraga michauxii | Saxifragaceae
|
| HYAN4 | Hydnocarpus anthelminticus Pierre ex Lanessan | hydnocarpus | Flacourtiaceae
|
| HYKU | Hydnocarpus kurzii (King) Warb. | chaulmoogra | Flacourtiaceae
|
| HYDNO | Hydnocarpus Gaertner | hydnocarpus | Flacourtiaceae
|
| HYARD2 | Hydrangea arborescens L. ssp. discolor (Ser. ex DC.) McClintock | Hydrangea cinerea | Hydrangeaceae
|
| HYARR | Hydrangea arborescens L. ssp. radiata (Walt.) McClintock | Hydrangea radiata | Hydrangeaceae
|
| HYARD4 | Hydrangea arborescens L. var. deamii St. John | Hydrangea cinerea | Hydrangeaceae
|
| HYARD3 | Hydrangea arborescens L. var. discolor Ser. ex DC. | Hydrangea cinerea | Hydrangeaceae
|
| HYARO | Hydrangea arborescens L. var. oblonga Torr. & Gray | Hydrangea arborescens | Hydrangeaceae
|
| HYARS | Hydrangea arborescens L. var. sterilis Torr. & Gray | Hydrangea arborescens | Hydrangeaceae
|
| HYAR | Hydrangea arborescens L. | wild hydrangea | Hydrangeaceae
|
| HYAS2 | Hydrangea ashei Harbison | Hydrangea cinerea | Hydrangeaceae
|
| HYCI3 | Hydrangea cinerea Small | ashy hydrangea | Hydrangeaceae
|
| HYMA7 | Hydrangea macrophylla (Thunb.) Ser. | French hydrangea | Hydrangeaceae
|
| HYPA | Hydrangea paniculata Sieb. | panicled hydrangea | Hydrangeaceae
|
| HYQU3 | Hydrangea quercifolia Bartr. | oakleaf hydrangea | Hydrangeaceae
|
| HYRA6 | Hydrangea radiata Walt. | silverleaf hydrangea | Hydrangeaceae
|