- Galax
- Gallant Soldier
- Gallberry
- Gambel Oak
- Garden angelica
- Garden cosmos
- Garden nasturtium
- Garland Daisy
- Garlic mustard
- German Chamomile
- Germander Speedwell
- Ghost Pipe
- Giant Bellflower
- Giant chain fern
- Giant goldenrod
- Giant Hogweed
- Giant milkweed
- Giant orchid
- Giant ragweed
- Giant red paintbrush
- Giant reed
- Giant sequoia
- Giant white fawn lily
- Glacier Lily
- Glandular Globe-thistle
- Glaucous Honeysuckle
- Goat willow
- Goat's rue
- Goatsbeard
- Goldback fern
- Golden Alexanders
- Golden bean
- Golden currant
- Golden marguerite
- Golden Pothos
- Golden ragwort
- Golden Wattle
- Golden wreath wattle
- Golden Yarrow
- Goldilocks Buttercup
- Goose Grass
- Gorse
- Goutweed
- Graceful spurge
- Graham's nipple cactus
- Grand collomia
- Grand fir
- Gray birch
- Gray dogwood
- Gray pine
- Gray's sedge
- Great blanketflower
- Great blue lobelia
- Great burnet
- Great horsetail
- Great masterwort
- Great mullein
- Great Plains yucca
- Great rhododendron
- Great stinging nettle
- Great Stonecrop
- Great Willowherb
- Greater bird's-foot-trefoil
- Greater burdock
- Greater butterfly-orchid
- Greater celandine
- Greater duckweed
- Greater Knapweed
- Greater periwinkle
- Greater plantain
- Greater Quaking Grass
- Greater stitchwort
- Greater whipwort
- Green alder
- Green Alkanet
- Green antelopehorns
- Green Arrow Arum
- Green ash
- Green Bristle Grass
- Green Buttonwood
- Green carpetweed
- Green comet milkweed
- Green dragon
- Green false hellebore
- Green strawberry
- Green-winged orchid
- Greenleaf manzanita
- Greenspot nightshade
- Grey alder
- Grey Field-speedwell
- Grey Mangrove
- Grey Willow
- Grey-cushioned Grimmia
- Grey-headed coneflower
- Grey-leaved Cistus
- Ground-ivy
- Groundsel tree
- Guelder-rose
- Guinea Grass
- Gum bumelia
- Gum Rock-rose
- Gumbo Limbo