Kerria Japonica or Japanese Rose
The genus is named after the botanist William Kerr and has only one species, native to central and western China but for centuries grown in Japan as an ornamental garden shrub. It is from Japan, too, that several varieties and cultivated forms have come. It has been cultivated in Europe since 1700 but not grown widely until 1860 when Siebold reintroduced the type species with single.
Japanese rose is a small, deciduous shrub growing to a height of about 1.5 to 2 m (5 to 6 ft) with strikingly green, wand-like slender branches usually arching towards the ground. The leaves are longish ovate, 2 to 5 cm (¾ to 2 in) in length, bright green above, a paler green beneath. The flowers, with five sepals and five petals and numerous stamens, appear from April to May. Also grown, in addition to the type species, is the variety pleniflora (flore plena), illustrated at thsee image right, with double flowers; aureo-vitata with yellow-striped branches, and pieta (aureovariegata) with green leaves edged white or yellow.
Japanese rose is propagated by softwood or hardwood as well as root cuttings. It thrives in soils that are light, well drained and nourishing and benefits from the addition of humus. The location should be a sunny one. The shrub is suitable for both large and small gardens but because of its twiggy habit is not particularly attractive except when in flower, and it is often planted together with perennials. It can also be put to good use in hedges or alongisde pathways.