Hooded Arrowhead
Hooked Bristlegrass
Hop
Hop Sedge
Hophornbeam
Hoptree
Horehound
Hornbeam
Horned Pondweed
Hornleaf Riverweed
Hornwort
Horse-gentian
Horsebalm
Horseflyweed
Horseradish
Horsetail
Horseweed
Huckleberry
Humped Bladderwort
Hyacinthbean
Hybrid Crack Willow
Hydrangea
Hydrilla
Hydrocotyle
Hyssopleaf Hedgenettle
Hyssopleaf Thoroughwort