- gardenia
- geophyte
- geotropic
- gherkin
- gingko
- glandiferous
- glomerule
- gemmule
- glandiform
- glandulose
- ginkgo
- glume
- gentian
- geotropism
- geranium
- gill
- glaucous
- gnarl
- gram
- grama
- gramma
- granadilla
- gooseberry
- gormless
- gorse
- grape-fruit
- grapefruit
- gourd
- greening
- greengage
- guaiac
- guava
- guelder rose
- gymnosperm
- guaiacum
- gynandrous
- gruelling
- gut
- gynaeceum
- gyrose
- hackberry
- hardy annual
- harebell
- haricot bean
- hastate
- haustoria
- hautboy
- halophyte
- hamamelidaceous
- haustorium
- hawthorn
- hazel
- hearts-ease
- heath
- heather
- heliophilous
- heliophobic
- heliotropic
- heliotropism
- helianthus
- heliotrope
- hellebore
- hemlock
- hemp
- henandchickens
- henbane
- henna
- hepatic
- hepatica
- hibiscus
- hilum
- hoboy
- hila
- hip
- hoarhound
- holm-oak
- holly
- holm
- hornbeam
- horse-bean
- honey locust
- honeysuckle
- horse-chestnut
- horse-radish
- honesty
- honey-cup
- hooded
- hop
- horehound
- horse-tail
- houseleek
- humble plant
- hyacinth
- hydrangea
- hydrophyte
- hydrotropic
- hydrotropism
- ice-plant
- hyssop
- ilang-ilang