Honckenya peploides
Sea Sandwort
Hopea ferrea
Malut
Hordeum distichon
Two-rowed Barley
Hordeum murinum
Wall Barley
Hordeum secalinum
Meadow Barley
Hordeum vulgare
Six-rowed Barley
Hornungia alpina
Perrenial Hutchinsia
Hornungia petraea
Hutchinsia
Hottonia palustris
Water-violet
Houttuynia cordata
Fish-plant
Humulus lupulus
Hop
Huperzia selago
Fir Clubmoss
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
Hymenophyllum tunbrigense
Tunbridge Filmy-fern
Hymenophyllum wilsonii
Wilson's Filmy-fern
Hyophorbe lagenicaulis
Bottle Palm
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