A stiff-habited, erect-growing evergreen shrub 6 to 20 ft high, branchlets becoming warty. Leaves 11⁄2 to 31⁄2 in. long, 1⁄2 to 1 in. wide; narrowly oval, tapering gradually to each end, upper surface glabrous, dull green, lower one covered with reddish brown scales; stalk 1⁄4 to 1⁄2 in. long. Flowers in terminal clusters of four to seven, produced in April and May; pedicels scaly, about 1⁄2 in. long. Calyx very small. Corolla 11⁄2 to 2 in. wide, rosy lilac, spotted with maroon on the upper side, the tube funnel-shaped, lobes wavy-margined. Stamens ten, downy towards the base. Ovary densely scaly; style glabrous. Bot. Mag., t. 7621. (s. Heliolepis)
Native of S.W. Szechwan (Muli region), N.W. Yunnan, and bordering parts of S.E. Tibet; introduced to Paris in 1889 by Père Delavay and thence to Britain. It is also cultivated from seeds sent later by Forrest and Rock. It is a somewhat stiff, dull-foliaged shrub but is very free-flowering. Its nearest ally is R. desquamatum, but that species has the leaves broadest below the middle and the scales on the undersides of the leaves are unequal, some being larger and darker than others, whereas in R. rubiginosum they are uniform.
R. rubiginosum, in the form originally introduced, was slightly tender at Kew, but the later introductions are usually reckoned to be perfectly hardy. The Award of Merit was given on May 3, 1960, to the clone 'Wakehurst', with Mallow Purple flowers, borne from axillary as well as terminal buds, forming clusters of up to twenty-five.
From the Supplement (Vol. V)
This, not unexpectedly, now includes R. desquamatum in synonymy. The best forms raised from seed-collections previously identified as R. desquamatum could be distinguished as Desquamatum group.