Berberis Thunbergii (Berberidaceae)
Japanese barberry belongs to the group of deciduous barberries as does also the only European species, Berberis vulgaris, which was formerly a common shrub of hedgerows and sunny hillsides. The latter is now severely limited in distribution because it is a host plant of grain rust and was for this reason eradicated in many places, but the Japanese barberry is the least prone to grain rust and is therefore widely cultivated in parks and gardens. Other deciduous species worthy of note are Berberis aggregata from western China, Berberis canadensis from North America, Berberis polyantha and Berberis wilsonae from western China.
Japanese barberry is a comparatively small shrub of spherical, compact habit, growing to a height of only about 2.5 m (8 ft). Theon slender stalks are coloured pale yellow, slightly reddish on the outside, and are borne singly or in clusters of two to four in late April and May. The fruits are bright red and about 1 cm (½ in) long. The leaves are about 1 to 3 cm (½ to 1 in) long, obovate, and greyish-green below; they turn a rich red in the autumn.
Japanese barberry is readily propagated by means of seeds. Like other deciduous barberries it requires light to dry soils and a sunny location. It is widely used in parks and gardens for its lovely coloration, especially for unclipped onramental hedges or to form a screen. Well known and very popular is the variety B. thunbergii atropurpurea with bronze-red leaves that turn carmine-red in the autumn.