Pentactina rupicola Nakai

A deciduous shrub 2 to 21⁄2 ft high; young shoots angled, glabrous, reddish; winter-buds silky. Leaves without stipules, alternate, very shortly stalked, mostly oblanceolate to obovate, wedge-shaped at the base, with usually three or five lobes or large teeth towards the apex, the lobes fine-pointed, often toothed, 3⁄4 to 11⁄2 in. long, 1⁄3 to 3⁄4 in. wide, glabrous above, more or less furnished with silky hairs beneath. Flowers small, white, produced in June and July on slender terminal pendulous panicles 11⁄2 to 3 in. long. Petals five, linear, 1⁄5 in. long; sepals five, triangular, persisting to the fruiting stage when they become much reflexed; stamens twenty, white, exposed. Each flower has five dry seed-vessels about 1⁄16 in. long.

Native of the Diamond Mountains of Korea and the only species known; introduced to the Arnold Arboretum in 1918 by Wilson, who found it common on cliffs. It is a graceful dwarf shrub with clustered stems, usually found wild growing in the crevices of rocks, but with more beauty in leaf and habit than in flower. It is quite hardy.