Tripterygium regelii Sprague & Takeda

A deciduous shrub of rambling or climbing habit, with angular, warted stems. Leaves alternate, oval or ovate, broadly wedge-shaped to rounded at the base, tapered at the apex to a long and slender point, 21⁄2 to 6 in. long, 11⁄2 to 4 in. wide, the margin set with rounded, blunt, incurved teeth, dark green above, and except for minute down on the midrib when quite young; stalk 1⁄4 to 3⁄4 in. long. Flowers yellowish white, about 1⁄3 in. wide, produced in a panicle at the end of the shoot, supplemented by clusters in the axils of the terminal leaves, the whole forming an inflorescence up to 8 or 9 in. long and 2 or 3 in. wide, petals five, roundish obovate; calyx small, with five rounded lobes; stamens five. Fruits three-angled, each angle conspicuously winged; the wings erect, about 5⁄8 in. long, 1⁄4 in. wide, membranous. The whole inflorescence is covered with short brown felt.

Native of the main and southern islands of Japan, and of Korea and Manchuria; introduced to the Arnold Arboretum by J. G. Jack in 1905 and thence to Kew. It is hardy, but not so fine a species as T. wilfordii. The fruits are greenish and rather like those of a wych elm with an extra wing.