Forsythia , is a genus of flowering plants in the olive family Oleaceae. There are about 11 species, mostly native to eastern Asia, but one native to southeastern Europe. Forsythia – also one of the plant's common names – is named after William Forsyth.
Description
Forsythia are deciduous shrubs typically growing to a height of and, rarely, up to with rough grey-brown bark. The leaves are borne oppositely and are usually simple, though sometimes trifoliate with a basal pair of small leaflets; they range between in length and, rarely, up to , with a margin that is serrated or entire (smooth). Twigs may be hollow or chambered, depending on the species.
The flowers are produced in the early spring before the leaves, bright yellow with a deeply four-lobed flower, the petals joined only at the base. These become pendent in rainy weather thus shielding the reproductive parts. The fruit is a dry capsule, containing several winged seeds.
There is a long-standing belief that forsythia flowers produce lactose, but lactose occurs only very rarely in natural sources other than milk, and attempts to find lactose in forsythia have been unsuccessful.
The genus is named after William Forsyth (1737–1804), a Scottish botanist who was a royal head gardener and a founding member of the Royal Horticultural Society.
Species
The following species of Forsythia have been documented: Forsythia europaea Degen & Bald. – Balkans in Albania and Serbia Forsythia giraldiana Lingelsh. – northwest China Forsythia × intermedia Zabel – an artificial garden hybrid between F. suspensa and F. viridissima Forsythia japonica Makino – Japan Forsythia koreana (Rehder) Nakai – Korea Forsythia likiangensis Ching & K.M.Feng – southwest China Forsythia × mandschurica Uyeki – northeast China Forsythia mira M.C.Chang – north central China Forsythia ovata Nakai – Korea Forsythia saxatilis (Nakai) Nakai – Korea Forsythia suspensa (Thunb.) Vahl – eastern and central China Forsythia togashii H.Hara – Japan (Shōdoshima) Forsythia velutina Nakai – Korea Forsythia viridissima Lindl. – eastern China
A genetic study does not fully match the traditionally accepted species listed above, and groups the species in four clades: (1) F. suspensa; (2) F. europaea—F. giraldiana; (3) F. ovata—F. japonica—F. viridissima; and (4) F. koreana—F. mandschurica—F. saxatilis. Of the additional species, F. koreana is usually cited as a variety of F. viridissima, and F. saxatilis as a variety of F. japonica; the genetic evidence suggests they may be better treated as distinct species.
Forsythias are used as food plants by the larvae of some Lepidoptera species including the brown-tail and Gothic moth.
Garden history
Two species of forsythia are at the heart of the selected forms and garden hybrids: Forsythia suspensa and F. viridissima. "These two species are, as it were, the founder-members of the forsythia family" writes Alice Coats; they were the earliest species brought into Western gardens from the Far East and they have each played a role in the modern garden shrubs.
Forsythia suspensa, the first to be noticed by a Westerner, was seen in a Japanese garden by the botanist-surgeon Carl Peter Thunberg, who included it (as a lilac) in his Flora Japonica 1784. Thunberg's professional connections lay with the Dutch East India Company, and F. suspensa reached Holland first, by 1833. In England, when it was being offered by Veitch Nurseries in Exeter at mid-century, it was still considered a rarity. Not all the varieties of suspensa are splaying and drooping, best seen hanging over a retaining wall; an erect form found by Fortune near Peking in 1861 was for a time classed as a species—F. fortunei.
Forsythia viridissima, meanwhile, had overtaken it in European gardens. The Scottish plant-hunter Robert Fortune "discovered" it—in a mandarin garden of the coastal city of Chusan (Zhoushan)—before he ever saw it growing wild in the mountains in Zhejiang province.
Forsythia × intermedia, as its name suggests, is a hybrid of F. suspensa and F. viridissima, introduced in continental Europe about 1880. Repeated crosses of the same two parents have made reiterations of F. × intermedia quite variable. A bud sport of a particularly showy (spectabilis) form is widely marketed as F. × intermedia 'Lynwood Variety'. This cultivar has gained the Royal Horticultural Society's Award of Garden Merit, as have F. × intermedia 'Courtalyn' and F. 'Courtasol'.