Hymenocallis fragrans
Spider Lily
Hypericum elodes
Marsh St John's-wort
Hypericum hirsutum
Hairy St John's-wort
Hypericum humifusum
Trailing St John's-wort
Hypericum maculatum
Imperforate St John's-wort
Hypericum perforatum
Perforate St John's-wort
Hypericum pulchrum
Slender St John's-wort
Hypochaeris maculata
Spotted Cat's-ear
Hypochaeris radicata
Cat's-ear
Hypopitys monotropa
Yellow Bird's-nest
Hyptis capitata
False Ironwort
Iberis amara
Wild Candytuft
Illecebrum verticillatum
Coral-necklace
Impatiens balsamina
Garden Balsam
Impatiens glandulifera
Indian Balsam
Impatiens noli-tangere
Touch-me-not Balsam
Indigofera hirsuta
Hairy Indigo
Ipomoea carnea
Pink Morning Glory
Iris foetidissima
Stinking Iris
Iris pseudacorus
Yellow Iris
Isatis tinctoria
Woad
Isolepis setacea
Bristle Club-rush
Ixora chinensis
Chinese Ixora
Jacobaea aquatica
Marsh Ragwort