- Galax
- Galinsoga
- Garlic Mustard
- Garlic, Wild
- Gentian, Stiff
- Gerardia, Slender
- Germander
- Gill-over-the-ground
- Goatsbeard
- Golden Alexander
- Golden Star
- Goldenrod, Blue-stemmed
- Goldenrod, Lance-leaved
- Goldenrod, Stout
- Goldenrod, Swamp
- Goldenrod, Tall
- Goldenrod, Zig-Zag
- Goutweed
- Grape, Riverbank
- Greater Coreopsis
- Great Angelica
- Great Laurel
- Ground Cherry, Clammy
- Ground Cherry, Virginia
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- Hairy Ruellia
- Hairyjointed Meadow Parsnip
- Harebell, Southern
- Hare Figwort
- Hawkweed, Field
- Hawkweed, Mouse Ear
- Hawkweed, Rough
- Heartleaf, Large-flowered
- Heartleaf, Virginia
- Hedge Mustard
- Hemp Nettle
- Henbit
- Hepatica, Round-lobed
- Hepatica, Sharp-lobed
- Hoary Puccoon
- Hobblebush
- Hog Peanut
- Honesty
- Honewort
- Horsebalm
- Horsemint
- Horse Nettle
- Horseweed
- Hound's Tongue
- Houstonia, Long-leaved
- Hyssop, Purple Giant
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