A deciduous shrub up to 25 ft high in the wild state, with reddish brown, stellately downy young shoots. Leaves elliptical, pointed, usually tapered but sometimes rounded at the base, shallowly toothed; 2 to 4 in. long, 3⁄4 to 2 in. wide; dark dull green above, greyish beneath, both sides soft and velvety to the touch; chief veins in five to seven pairs; stalk 1⁄6 in. or less long. Flowers white, about 1 in. wide, produced on short leafy shoots as in S. langkongensis. Corolla lobes downy outside and at the margins. Calyx bell-shaped, 1⁄4 in. long, very downy, minutely toothed or almost entire; flower-stalk about 1⁄4 in. long, often thickening towards the calyx and giving it a funnel-like shape.
Native of Yunnan and probably of bordering Burma; discovered by Forrest in 1913 and introduced by him in 1919 from the Mekong-Salween divide (F. 18249, shrub 10-12 ft high, growing in open thickets). It is now rare.
S. langkongensis W.W. Sm. – Another of Forrest’s discoveries and introductions, allied to the preceding and also shrubby, differing in its smaller leaves whiter beneath and less velvety, and its less toothed calyx. Forrest found it in flower in 1910 as a shrub 1 to 4 ft high, but later collections were slightly taller. He introduced it during his 1917-19 expedition (F. 16929).
Neither of these species is superior to S. wilsonii and both are probably more tender or at least more demanding of summer heat.