An evergreen shrub or small tree, up to 30 ft high; branchlets slender, clad with stalked glands; bud-scales deciduous. Leaves leathery, oval, oblong-oval, obovate, obtuse to broadly rounded at the apex, rounded to subcordate at the base, up to 61⁄2 in. long and 33⁄4 in. wide, clad beneath with a woolly greyish or light brown indumentum which gradually wears away; petiole glandular-bristly, up to 3⁄4 in. long. Inflorescence a terminal umbel of twelve to fifteen flowers, opening in March or April; pedicels about 3⁄8 in. long, glandular. Calyx cup-shaped, pink, with short, irregular, gland-fringed lobes. Corolla five-lobed, funnel-campanulate, deep crimson or deep rosy pink, about 11⁄2 in. wide. Ovary densely covered with stalked glands; style glabrous. (s. Barbatum ss. Glischrum)
A native of the eastern Himalaya, found by Ludlow and Sherriff in 1936 on the Tibetan side of the range (Chayul and Tsari) at 10,000 to 12,000 ft, and introduced by them. Although not so fine in flower as R. barbatum, which it somewhat resembles, it has striking foliage.
R. exasperatum Tagg – This species resembles R. erosum in its broad leaves, rounded at the apex, but their undersurface is glandular bristly (not woolly, later glabrous, as in R. erosum), and the foliage bud-scales are persistent. R. exasperatum was introduced by Kingdon Ward in 1926 from the Seinghku valley in north-west Burma, where it grows at 10,000 ft 'only in the tanglewood on precipitous broken rock faces, where water drips continuously and everything is moss bound'. From there it ranges west through the Delei valley to the eastern end of the Himalaya, where it was found on several occasions by Ludlow and Sherriff and their companions. It is rather more tender than R. erosum and less attractive in its flowers (which, at least in the Kingdon Ward forms, are brick-red with an orange flush). The young growths are richly tinted.