A deciduous shrub up to 10 ft high; young shoots covered densely with a white wool. Leaves oblong-lanceolate, tapered at the base, long and slenderly pointed, generally slightly toothed, sometimes almost entire: 4 to 8 in. long, 11⁄2 to 21⁄2 in. wide; dull green and slightly downy above, covered like the young shoots with white wool below; stalk about 1⁄3 in. long. Panicles 6 to 18 in. long, about 1 in. wide, slenderly cylindrical, usually coming in threes from the end of the current season's growth in late summer and autumn, and composed of closely packed, few-flowered, shortly stalked cymes. Corolla 1⁄3 in. long, about 1⁄/6 in. across the four roundish lobes, lilac-coloured, with orange in the throat, very downy inside and out. Calyx 1⁄8 in. long, downy, with slender erect lobes. Stamens inserted between the middle and the apex of the corolla tube.
Native of W. Szechwan, China; discovered and introduced by Wilson in 1908. The species is cultivated in the Arnold Arboretum and plants under the name are grown in English gardens. It is notable for the slenderness of its long panicles. It resembles B. nivea in leaf, etc., but that species has a much shorter, pyramidal panicle and has the stamens close to the mouth of the corolla-tube.
From the Supplement (Vol. V)
As remarked on page 458, this species bears a strong resemblance to B. nivea. It is in fact included in it by Leeuwenberg.