Ground Ivy 
A low growing, stoloniferous creeping, perennial weed which may occasionally encroach into neglected lawns, particularity from hedge lines, and where shady conditions are prominent. However, it is an uncommon turfgrass weed where areas have minimal but regular maintenance carried out. Its leaves are oval shaped, with a wavy edge, typically being 20 to 50mm in diameter. It prefers moist conditions, heavier loamy soils and will adapt to a wide range of soil pH levels. It flowers from March to June, having blue-violet coloured flowers to about 20mm in diameter. Its scientific name is Glechoma hederacea.
Groundsel
An annual weed, sometimes ephemeral, of disturbed soil and newly seeded areas, especially where sterilised soil has not been used. It is easily controlled by regular mowing. It will grow in a wide range of soil conditions, from acidic to alkaline, dry to moist and over a range of soil types; it doesn't, however, like shade. It has small yellow flowers which can appear in any month of the year. Its scientific name is Senecio vulgaris.
Hairy Bittercress
A common annual weed of lesser maintained amenity surfaces and lawns. It has small pinnate leaves are arranged in a rosette pattern. It prefers drier more sunny situations. It flowers from March to September, having very small white flowers, with 4 stamens to distinguish it from Wavy Bittercress. Its scientific name is Cardamine hirsuta.
Heath Bedstraw
An uncommon perennial weed of lesser maintained and neglected turf surfaces, growing as a mat forming weed. Its scientific name is Galium saxatile. It typically has 6 leaves arranged in a whorl fashion around the stem. The main flowering period is June to August, with very small white flowers. It has preference for dry, sandy, acidic soils (considered a calcifuge), in open to lightly shaded conditions.
Heath Pearlwort
An uncommon perennial weed of dry sandy heath soils, so it is limited to these few conditions in the UK. The weed typically produces a circular, low growing mat, is not creeping, but does have hairy stems. It flowers from June to August, having a small white 5-petaled flower. Its scientific name is Sagina subulata.
Hedgerow Cranes-bill
A perennial weed of lesser maintained turf surfaces, especially bordering hedgerows or shrub borders. A relatively upright plant, lightly hairy, whilst it flowers from June to August, having larger flowers than those on Doves-foot Cranes-bill, being more purple coloured. It is common on moist soils, that are not acidic. Its scientific name is Geranium pyrenaicum.
Himalayan Balsam
An annual invasive plant of wet ditches, riverbanks and damp woodlands, especially on the banks of streams or perimeter ditches to golf course and playing fields, being up to 2-m in height. The 5 whitish-pink petals appear as 3 petals because 2 x 2 are fused with one is unfused, with flowering taking place between July and October. The stems are reddish or with reddish tinges, whilst the leaf edges have fine teeth being attached as pairs or whorls of 3 to a stem. Its scientific name is Impatiens glandulifera and also has the common name of Indian Balsam.
Hoary Plantain
An uncommon perennial weed of turf surfaces, similar to Broad-Leaved Plantain. Its scientific name is Plantago media. It is a broad-leaved weed, preferring drier, neutral to chalky soils (which can include well drained clay soils overlying chalk areas), without any shade. Its leaves are oval, lightly hairy (downy), having typically 5 veins, but anywhere from 3 to 9 veins might be present. The leaves will typically be more ground hugging rather than upright, often being just a few within a rosette, not dying in winter. It flowers from May to August, having pinkish purple coloured, at the base,
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Hypochaeris radicata
The scientific name for the weed Cat's-Ear.
Jacobaea vulgaris