Holmskioldia sanguinea
Chinese Hat Plant
Honckenya peploides
Sea Sandwort
Hordeum distichon
Two-rowed Barley
Hornungia alpina
Perrenial Hutchinsia
Hornungia petraea
Hutchinsia
Houttuynia cordata
Fish-plant
Humulus lupulus
Hop
Hyacinthoides hispanica
Spanish Bluebell
Hyacinthoides italica
Italian Bluebell
Hyacinthoides non-scripta
Bluebell
Hyacinthoides x massartiana
Garden Bluebell
Hydrangea macrophylla
Hydrangea
Hydrangea paniculata
Hydrangea (paniculata)
Hydrangea petiolaris
Climbing Hydrangea
Hydrangea quercifolia
Oak-leaved Hydrangea
Hydrangea sp
Hydrocharis morsus-ranae
Frogbit
Hydrocotyle hirta
Hydrocotyle vulgaris
Marsh Pennywort
Hylotelephium telephium
Orpine
Hymenocallis fragrans
Spider Lily
Hymenocallis littoralis
Beach Spider Lily
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 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
Hypochaeris maculata
Spotted Cat's-ear
Hypochaeris radicata
Cat's-ear
Hypopitys monotropa
Yellow Bird's-nest
Iberis amara
Wild 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
Indigofera suffruticosa
Guatemalan Indigo
Inula conyzae
Ploughman's-spikenard
Inula helenium
Elecampane
Ipomoea aquatica
Water Spinach
Ipomoea carnea
Pink Morning Glory
Ipomoea hederacea
Ivy-leaved Morning Glory
Ipomoea nil
Picotee Morning Glory
Ipomoea obscura
Obscure Morning Glory
Ipomoea tricolor
Mexican Morning Glory
Ipomoea triloba
Aiea Morning Glory
Iris
Iris,#reticulata#bulbous#type.
Iris douglasiana
Iris (douglasiana)
Iris foetidissima
Stinking Iris
Iris pseudacorus
Yellow Iris
Iris sibirica
Siberian Iris
Iris unguicularis
Algerian Iris
Isatis tinctoria
Woad
Isolepis setacea
Bristle Club-rush
Ixora chinensis
Chinese Ixora
Jacobaea aquatica
Marsh Ragwort
Jacobaea vulgaris
Common Ragwort