| Scientific Name | Common Name(s) | Life History | Growth Form | |
|---|---|---|---|---|
| Genista racemosa | sweet broom, florists' broom, Canary Island broom, Easter broom | Perennial | shrub | |
|
Gentiana cruciata | cross gentian, crosswort gentian, star gentian | Perennial | forb |
| Geranium lucidum | shining geranium, shining crane's-bill | Annual | forb | |
|
Geranium purpureum | little robin | Annual | forb |
| Geranium retrorsum | New Zealand geranium, common crane's-bill | Perennial | forb | |
|
Geranium robertianum | herb-Robert, red robin, death come quickly, stinking Bob, squinter-pip, crow's foot, Roberts geranium | Annual | forb |
| Geranium sanguineum | Bloody Cranesbill, bloody geranium | Perennial | forb | |
|
Geranium sanguineum var. striatum | striped bloody cranesbill, hardy geranium | Perennial | forb |
|
Glebionis segetum | corn chrysanthemum, corndaisy, corn-marigold | Annual | forb |
|
Gleditsia triacanthos | honey locust, sweet-bean, sweet-locust | Perennial | shrub |
|
Glycyrrhiza glabra | licorice, licorice-root | Perennial | forb |
|
Grevillea robusta | silkoak, Australian silky-oak | Perennial | tree |
|
Grevillea rosmarinifolia | rosemary grevillea | Perennial | shrub |
|
Gunnera tinctoria | Chilean gunnera, Chilean rhubarb | Perennial | forb |
|
Gypsophila paniculata | Baby's-breath | Perennial | forb |
|
Halimodendron halodendron | common salttree, Russian salt tree | Perennial | shrub |
|
Hedera helix | English Ivy | Perennial | vine |
| Hedera helix 'Thorndale' | English Ivy | Perennial | vine | |
|
Hedera hibernica | Irish ivy, Atlantic ivy | Perennial | vine |
|
Helianthus tuberosus | Jerusalem artichoke, earth apple, sunchoke | Perennial | forb |
| Helichrysum petiolare | licorice-plant, silver-bush everlasting-flower | Perennial | forb | |
|
Heliotropium amplexicaule | blue heliotrope, clasping heliotrope | Perennial | forb |
|
Heliotropium supinum | prostrate heliotrope, spreading heliotrope | Annual | forb |
|
Hemerocallis 'Stella d'Oro' | daylily | Perennial | forb |
|
Heracleum mantegazzianum | giant hogweed, cartwheel-flower | Perennial | forb |