Leadwort — Plumbago is a genus of 10-20 species of flowering plants in the family Plumbaginaceae, native to warm temperate to tropical regions of the world. Common names include plumbago and leadwort (names which are also shared by the genus Ceratostigma). The name Plumbago is derived from Latin plumbum (“lead”), either from the lead-blue flower colour of some species (OED), …

Hawthorn, English — Hawthorn (Crataegus) is a large genus of shrubs and trees in the family Rosaceae, native to temperate regions of the Northern Hemisphere in Europe, Asia and North America. The name hawthorn was originally applied to the species native to northern Europe, especially the Common Hawthorn C. monogyna, and the unmodified name is often so used in Britain …

Gladiolus — Gladiolus (from Latin, the diminutive of gladius, a sword) is a genus of flowering plants in the iris family (Iridaceae). Sometimes called the sword lily, the most widely-used English common name for these plants is simply gladiolus (plural gladioli or gladioluses). The genus Gladiolus contains about 260 species, of which 250 are native to sub-Saharan Africa, mostly South …

Hollyhock — The hollyhocks comprise about 60 species of flowering plants in the genus Alcea in the mallow family Malvaceae, native to southwest and central Asia. They are biennial or short-lived perennial plants growing to 3.5 m tall, with broad, rounded, palmately lobed leaves and numerous flowers, pink or yellow in the wild species, on the erect central stem. Alcea …

Holly — Holly (Ilex) is a genus of about 600 species of flowering plants in the family Aquifoliaceae, and the only living genus in that family. One other genus, the monotypic Nemopanthus (Mountain Holly), was formerly separated from Ilex on the basis that its flowers have a reduced calyx and narrow petals, and also in cytology, being tetraploid, whereas Ilex …

Hickory — Trees in the genus Carya (from Ancient Greek kary “nut”) are commonly known as Hickory. The genus includes 17-19 species of deciduous trees with pinnately compound leaves and large nuts. A dozen or so species are native to North America (11–12 in the United States, 1 in Mexico), and 5–6 species from China and Indochina. Another Asian species, …

Hibiscus — Hibiscus, or rosemallow, is a large genus of about 200–220 species of flowering plants in the family Malvaceae (the mallow family, along with members like cocoa, cotton, okra, baobab and durian) native to warm temperate, subtropical and tropical regions throughout the world. The genus includes both annual and perennial herbaceous plants, and woody shrubs and small trees. The …

Hemlock — Tsuga is a genus of conifers in the family Pinaceae. The common name hemlock is derived from a perceived similarity in the smell of the crushed foliage to that of the unrelated herb poison hemlock; see hemlock for other senses of the word. Unlike the herb, the species of Tsuga are not poisonous. There are between eight and …

Heliotrope — The Heliotropes (Heliotropium) is a genus of plants in the family Boraginaceae with 250 to 300 species. Several of them are popular garden plants, most notably Heliotropium arborescens. Some species are weeds and many are toxic if eaten in large quantities. The name Heliotrope (Helios is Greek for sun, tropein means turn) derives from the fact that these …

Heather — Calluna vulgaris is the sole species in the genus Calluna in the family Ericaceae. It is the true Heather of Europe, and National Flower of Norway. However it also has an affiliation to Scotland. It is a small perennial shrub growing to 20-50 cm tall (rarely to 1 m), and is found widely in Europe and Asia Minor …