Hairgrass, Wavy [Deschampsia flexuosa]
Hayfield Tarweed [Hemizonia congesta]
Heath, Crossleaf [Erica tetralix]
Heather [Calluna vulgaris]
Hedera helix [English Ivy]
Helianthemum nummularium [Sun Rose]
Helianthus annus [Sunflower]
Hellroot [Orobanche minor]
Helxine soleirolii
Hemigraphis alternata [Red Ivy]
Hemizonia congesta [Hayfield Tarweed]
Hemlock, Eastern [Tsuga canadensis]
Hemlock, Poison [Conium maculatum]
Heterosigma akashiwo [A Marine Raphidophyte]
Heterotheca subaxillaris [Camphorweed]
Hilograss [Paspalum conjugatum]
Hiziki (Brown Seaweed) [Hizikia fusiforme]
Hizikia fusiforme [Hiziki (Brown Seaweed)]
Holcus lanatus [Common Velvetgrass]
Hippeastrum [Amaryllis]
Hordeum vulagare [Barley]
Hydrilla verticillata [Water Thyme]
Hymenocallis littoralis [Spider Lily]
Hyparrhenia rufa [Jaragua]
Hypericum perforatum [St. John's Wort]