Heracleum mantegazzianum
Giant Hogweed
Heracleum sphondylium
Hogweed
Herminium monorchis
Musk Orchid
Hesperis matronalis
Dame's-violet
Hibiscus tiliaceus
Sea Hibiscus
Hieracium cillense
Craig y Cilau Hawkweed
Hippeastrum puniceum
Amaryllis Lily
Hippocrepis comosa
Horseshoe Vetch
Hippuris vulgaris
Mare's-tail
Hirudo medicinalis
Honckenya peploides
Sea Sandwort
Hordeum murinum
Wall Barley
Hornungia petraea
Hutchinsia
Humulus lupulus
Hop
Huperzia selago
Fir Clubmoss
Hyacinthoides hispanica
Spanish Bluebell
Hyacinthoides non-scripta
Bluebell
Hydrocotyle hirta
Hydrocotyle vulgaris
Marsh Pennywort
Hygrocybe calyptriformis
Pink Waxcap
Hygrocybe coccinea
Scarlet waxcap
Hygrocybe conica
Blackening Wax Cap
Hygrocybe miniata
Hygrocybe psittacina
Parrot Waxcap
Hylotelephium telephium
Orpine
Hymenocallis fragrans
Spider Lily
Hymenophyllum tunbrigense
Tunbridge Filmy-fern
Hymenophyllum wilsonii
Wilson's Filmy-fern
Hypericum androsaemum
Tutsan
Hypericum calycinum
Rose-of-Sharon
Hypericum elodes
Marsh St John's-wort
Hypericum hirsutum
Hairy St John's-wort
Hypericum humifusum
Trailing St John's-wort
Hypericum perforatum
Perforate St John's-wort
Hypholoma fasciculare
Sulphur Tuft
Hypochaeris radicata
Cat's-ear
Hypopitys monotropa
Yellow Bird's-nest
Hyptis capitata
False Ironwort
Iberis amara
Wild Candytuft
Ilex aquifolium
Holly
Impatiens glandulifera
Indian Balsam
Impatiens noli-tangere
Touch-me-not Balsam
Inachis io
European Peacock Butterfly
Ipomoea carnea
Pink Morning Glory
Ipomoea hederacea
Ivy-leaved Morning Glory
Ipomoea obscura
Obscure Morning Glory
Iris foetidissima
Stinking Iris
Iris pseudacorus
Yellow Iris
Isatis tinctoria
Woad
Isoetes lacustris
Quillwort
Jacobaea aquatica
Marsh Ragwort
Jasione montana
Sheep's-bit
Jatropha podagrica
Gout-plant
Juncus articulatus
Jointed Rush
Juncus compressus
Round-fruited Rush
Juncus gerardii
Saltmarsh Rush
Juncus squarrosus
Heath Rush
Juniperus communis
Juniper
Justicia brandegeeana
Shrimp Plant
Kickxia elatine
Sharp-leaved Fluellen
Knautia arvensis
Field Scabious
Laburnum anagyroides
Laburnum
Laburnum x watereri
Hybrid Laburnum
Laetiporus sulphureus
Sulphur Polypore
Lagerstroemia speciosa
Giant Crepe-myrtle
Lamiastrum galeobdolon
Yellow Archangel
Lamium album
White Dead-nettle
Lamium amplexicaule
Henbit Dead-nettle
Lantana camara
Common Lantana
Lapsana communis
Nipplewort