Hyoscyamus niger
Henbane
Hypericum
Hypericum androsaemum
Tutsan
Hypericum calycinum
Rose-of-Sharon
Hypericum elodes
Marsh St John's-wort
Hypericum forrestii
Forrest's Tutsan
Hypericum hircinum
Stinking Tutsan
Hypericum hirsutum
Hairy St John's-wort
Hypericum humifusum
Trailing St John's-wort
Hypericum maculatum
Imperforate St John's-wort
Hypericum montanum
Pale St John's-wort
Hypericum perforatum
Perforate St John's-wort
Hypericum pulchrum
Slender St John's-wort
Hypericum tetrapterum
Square-stalked St John's-wort
Hypericum x caesariense
Hypericum x desetangsii
Des Etangs' St John's-wort
Hypericum x inodorum
Tall Tutsan
Hypnum cupressiforme
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
Iberis umbellata
Garden Candytuft
Ilex aquifolium
Holly
Illecebrum verticillatum
Coral-necklace
Impatiens balsamina
Garden Balsam
Impatiens glandulifera
Indian Balsam
Impatiens noli-tangere
Touch-me-not Balsam
Impatiens parviflora
Small Balsam
Impatiens walleriana
Busy Lizzie
Imperata
Imperata cylindrica
Cogon Grass
Indigofera hirsuta
Hairy Indigo
Indigofera suffruticosa
Guatemalan Indigo
Inula conyzae
Ploughman's-spikenard
Inula helenium
Elecampane
Ipomoea aquatica
Water Spinach
Ipomoea batatas
Sweet Potato
Ipomoea carnea
Pink Morning Glory
Ipomoea hederacea
Ivy-leaved Morning Glory
Ipomoea obscura
Obscure Morning Glory
Ipomoea tricolor
Mexican Morning Glory
Ipomoea triloba
Aiea Morning Glory
Iris
Iris
Iris douglasiana
Iris (douglasiana)
Iris foetidissima
Stinking Iris
Iris pseudacorus
Yellow Iris
Iris sibirica
Siberian Iris
Iris unguicularis
Algerian Iris
Isatis tinctoria
Woad
Isoetes echinospora
Spring Quillwort
Isoetes lacustris
Quillwort
Isolepis setacea
Bristle Club-rush
Ixora chinensis
Chinese Ixora
Jacobaea aquatica
Marsh Ragwort
Jacobaea vulgaris
Common Ragwort
Jacobaea x ostenfeldii
Jasione montana
Sheep's-bit
Jasminum nudiflorum
Winter Jasmine
Jatropha gossypiifolia
Bellyache Bush
Jatropha integerrima
Jatropha podagrica
Gout-plant
Juglans regia
Walnut
Juncus acutiflorus
Sharp-flowered Rush
Juncus acutus
Sharp Rush
Juncus articulatus
Jointed Rush
Juncus bufonius
Toad Rush
Juncus bulbosus
Bulbous Rush
Juncus compressus
Round-fruited Rush