An evergreen shrub up to 4 ft high; shoots slender, floccose when young and slightly glandular. Leaves leathery, oblong-elliptic, or broadest slightly above or below the middle, up to 4 in. long and 11⁄2 in. wide, obtuse at the apex, cuneate to rounded at the base, dark green and glabrous above, lower surface glandular and coated with a fawn-coloured felt; petiole very short. Inflorescence a loose truss of three to ten flowers, opening in April; rachis very short; pedicels about 5⁄8 in. long. Calyx minute. Corolla broadly campanulate, about 1 in. deep and twice as wide, claret-red to deep vivid crimson, with darker markings on the upper side, five-lobed. Stamens ten, filaments downy at the base. Ovary conoid, glabrous, or almost so.
This species was found by Forrest in S.E. Tibet under Ka-kar-po on the Mekong-Salween divide in 1918, and introduced by him the same year. It is an anomalous species, originally placed in series Taliense, subseries Roxieanum, though Dr Cowan pointed out that the leaf-indumentum is uncharacteristic of that group and very like that of R. citriniflorum (s. Neriiflorum ss. Sanguineum). It received an Award of Merit when shown from Exbury on April 30, 1940. R. microgynum Balf. f. & Forr., also from Ka-kar-po, is very closely allied, and was described earlier.