Common names: I
- ice man fungus
- ice plant
- iceberg lettuce
- Iceland poppy
- immortelle
- imperial lewisia
- India red water lily
- Indian azalea
- Indian banyan tree
- Indian barberry
- Indian clock vine
- Indian cress
- Indian date
- Indian hawthorn
- Indian hemp
- Indian lilac
- Indian mallow
- Indian mayapple
- Indian mulberry
- Indian mustard
- Indian nightshade
- Indian paintbrush
- Indian physic
- Indian pokeweed
- Indian potato
- Indian prune
- Indian rhubarb
- Indian shot
- Indian tea
- Indian tobacco
- indigo
- indigo woodland sage
- intermediate periwinkle
- interrupted fern
- Iranian poppy
- iris
- iris-like cymbidium
- Irish ivy
- Irish saxifrage
- Italian alder
- Italian arum
- Italian aster
- Italian bugloss
- Italian clematis
- Italian clover
- Italian cypress
- Italian honeysuckle
- Italian maple
- Italian millet
- Ithuriel's spear
- Ives' fournerved daisy
- ivory curl tree
- ivory thistle
- ivy
- ivy-leaved cyclamen
- ivy-leaved morning glory
- ivy-leaved pelargonium
- ivy-leaved toadflax