Shrub, 1–4.5 m. Leaves 7–14 × 3.5–6.5 cm, elliptic to ovate, glabrous above, with a sparse discontinuous indumentum of dark brown fasciculate hairs, to more or less glabrous. Flowers 5–8, in a lax truss, white to pale mauve or lilac, with or without flecks, funnel-campanulate, nectar pouches lacking, 25–50 mm; ovary almost glabrous, style glabrous. Flowering April-May. Royal Horticultural Society (1997).
Distribution Bhutan China S Tibet India Sikkim, Bengal Nepal E
Habitat 3,000–4,000 m
RHS Hardiness Rating H6
Conservation status Least concern (LC)
White-flowered forms with leaves more or less glabrous beneath have been referred to R. heftii Davidian. This species is closely allied to R. campanulatum and treated by some as a variety of that species. Natural hybrids between R. wallichii and R. arboreum are found in cultivation. Royal Horticultural Society (1997).