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This genus, consisting of five or six species of deciduous shrubs, commemorates William Forsyth, once superintendent of the Royal Gardens at Kensington (1737-1804). They are allied to the lilacs and jasmines, and have opposite, simple or sometimes trifoliate leaves and yellow flowers produced before the leaves on short stalks from single or clustered many-scaled buds borne at the joints of the previous year's wood, each bud producing one, two, or occasionally up to four or five flowers. Calyx four-lobed, green. Corolla also four-lobed, the lobes united at the base into a short tube. Stamens two. Style one, either long or short; both long-styled and short-styled plants occur in each species and cross-pollination between them is usually necessary for the production of fruits. For this reason the fruits, which are many-seeded capsules, are rarely borne in this country except on some tetraploids of garden origin but are mentioned in the account that follows in order to complete the description. One species is a native of S.E. Europe; the others are from E. Asia.
With one exception, all the species of Forsythia have lamellate pith, i.e., the stems, cut lengthways, are seen to be filled with transverse plates of pith. But in F. suspensa the internodes are hollow, the pith being confined to the nodes. In F. × intermedia the internodes are mostly irregularly lamellate or hollow.
The forsythias are very easily cultivated and have no objection to lime, but are gross feeders and prefer a good garden soil. They are propagated very easily by cuttings made of half-ripened shoots. The hybrid 'Spectabilis', and no doubt many other sorts, can be increased by cuttings of ripened wood about 1 ft long, placed in light soil in the open ground at any time between October and January. There is no need for annual pruning, but once the plant is well established a few of the oldest stems should be cut out each year. Plants grown on walls, or in other positions where growth has to be restricted, should be trimmed after flowering. The finest display of flowers comes from plants that have been sited where they can grow freely yet are not so remote from the comings and goings of daily life that the birds can destroy their flower-buds undisturbed.
Revised with the assistance of Mr P. S. Green of the Kew Herbarium.