Humulus lupulus
Hop
Huperzia selago
Fir Clubmoss
Hyacinthoides non-scripta
Bluebell
Hydrocharis morsus-ranae
Frogbit
Hydrocotyle vulgaris
Marsh Pennywort
Hylotelephium telephium
Orpine
Hymenophyllum spp.
Filmy-ferns
Hymenophyllum tunbrigense
Tunbridge Filmy-fern
Hymenophyllum wilsonii
Wilson's Filmy-fern
Hypericum androsaemum
Tutsan
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 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
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 noli-tangere
Touch-me-not Balsam
Inula conyzae
Ploughman's-spikenard
Iris foetidissima
Stinking Iris
Iris pseudacorus
Yellow Iris
Isoetes echinospora
Spring Quillwort
Isoetes lacustris
Quillwort
Isolepis setacea
Bristle Club-rush
Jacobaea x ostenfeldii
Jasione montana
Sheep's-bit
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
Juncus effusus
Soft-rush
Juncus gerardii
Saltmarsh Rush
Juncus inflexus
Hard Rush
Juncus squarrosus
Heath Rush
Juncus subnodulosus
Blunt-flowered Rush
Juniperus communis
Juniper
Knautia arvensis
Field Scabious
Laburnum anagyroides
Laburnum
Lactuca saligna
Least Lettuce
Lactuca virosa
Great Lettuce
Lamiastrum galeobdolon
Yellow Archangel
Lamium purpureum
Red Dead-nettle
Lathraea squamaria
Toothwort
Lathyrus japonicus
Sea Pea
Lathyrus linifolius
Bitter-vetch
Lathyrus nissolia
Grass Vetchling
Lathyrus pratensis
Meadow Vetchling
Lathyrus sylvestris
Narrow-leaved Everlasting-pea
Leontodon hispidus
Rough Hawkbit
Leontodon saxatilis
Lesser Hawkbit
Lepidium heterophyllum
Smith's Pepperwort
Lepidium latifolium
Dittander
Leucanthemum vulgare
Oxeye Daisy
Leucojum aestivum
Summer Snowflake
Leymus arenarius
Lyme-grass
Ligustrum vulgare
Wild Privet
Limbarda crithmoides
Golden-samphire
Limonium binervosum agg.
Rock Sea-lavender (Tywyn Trewan)
Limonium vulgare
Common Sea-lavender
Limosella aquatica
Mudwort
Limosella australis
Welsh Mudwort