Hazel _Corylus_ 56 Hedgehyssop _Gratiola_ 43 Hedgemustard _Sisymbrium officinale_ 53 Heliopsis _Heliopsis_ 44 Heliotrope _Heliotropium_ 44 Hemicarpha _Hemicarpha_ 28 Hemp _Cannabis_ 38 Henbit _Lamium amplexicaule_ 46 Hibiscus _Hibiscus_ 44 Hickory _Carya_ 56 Hilaria _Hilaria_ 22 Hoarhound _Marrubium_ 47 Hogpeanut _Amphicarpa_ 30 Holly _Ilex_ 57 Hollyfern _Polystichum_ 28 Honeylocust _Gleditsia_ 31, 57 Honeysuckle _Lonicera_ 47, 57 Hop _Humulus_ 45 Hophornbeam _Ostrya_ 57 Hoptree _Ptelea_ 57 Hornwort _Ceratophyllum_ 38 Horsebean _Vicia faba_ var. _equina_ 34 Horsegentian _Triosteum_ 54 Horsenettle _Solanum carolinense_ 53 Horseradish _Armoracia lapathifolia_ 36 Horsetail _Equisetum_ 28 Horseweed _Conyza canadensis_ 40 Houndstongue _Cynoglossum_ 40 Hyacinthbean _Dolichos_ 31 Hymenopappus _Hymenopappus_ 45 Hymenoxys _Hymenoxys_ 45 Hyparrhenia _Hyparrhenia_ 22 Indiangrass _Sorghastrum_ 25 Indianplantain _Cacalia_ 38 Indigo _Indigofera_ 32 Iris _Iris_ 29 Ironplant _Haplopappus spinulosus_ 44 Ironweed _Vernonia_ 55 Isopyrum _Isopyrum_ 45 Jackinthepulpit _Arisaema_ 29 Japanesemillet _Echinochloa crusgalli_ var. _frumentacea_ 21 Jaragua _Hyparrhenia rufa_ 22