A dwarf evergreen shrub, ultimately a yard or mote high, of bushy, densely leafy habit; young shoots covered with red and yellow scales. Leaves borne along nearly the whole of the shoots, half a dozen to the inch, oval or ovate, round-ended, 3⁄4 to 13⁄4 in. long, half as much wide, dark dull green above, rusty yellow beneath, both surfaces very scaly; stalk 1⁄10 to 1⁄/6 in. long. Flowers opening in March and April in close clusters of five to ten; pedicels up to 1⁄4 in. long. Calyx deeply cut into five ovate or oblong lobes about 1⁄/6 in. long, fringed with hairs. Corolla a vivid purple-blue, about 1 in. wide, with five spreading lobes and a funnel-shaped base that is hairy in the throat. Stamens ten, conspicuously exposed, hairy towards the base, the stalks reddish; anthers brown. Ovary scaly; style red, hairy at the base. Bot. Mag., t. 8963. (s. Lapponicum)
Native of N.W. Yunnan and S.W. Szechwan at 11,000 to 13,000 ft, in open places, boggy pastures, cliff-ledges, etc.; discovered by Forrest in 1917 on the Kari pass, Mekong-Yangtse divide, and cultivated from seeds he sent in that year and many times later. It is one of the most richly coloured and desirable of the series, and is perfectly hardy. The flowers vary in the intensity of the colouring and in the proportion of blue in the purple; they are almost indigo in some forms. The white centre to the corolla, usually a prominent feature of this species, comes from the hairs in the throat and at the base of the stamens.
It received an Award of Merit on May 3, 1927, when shown from Werrington Park, Cornwall, by A. M. Williams (flowers intense violet-blue) and a First Class Certificate when shown by Lionel de Rothschild, Exbury, on April 4, 1933 (flowers intense purple). It received an Award of Garden Merit in 1938.
From the Supplement (Vol. V)
The cultivated plant which is the type of R. cantabile certainly belongs to R. russatum, but the seed collection from which it is supposed to have been raised (F. 16583) is R. rupicola. This species and R. russatum are essentially similar, the key difference between them being that in R. rupicola the calyx-lobes have a central band of scales, lacking in R. russatum. Natural hybrids between the two occur in the wild on the Chienchuan-Mekong divide. Several Forrest Collections from such swarms were originally identified as R. russatum. (Rev. Lapp., pp. 13, 59).