Shrub or small tree, 2.5–9 m; bark rough. Leaves 13.5–15 × 5.5–6.2 cm, upper surface with impressed veins, lower surface with a two-layered indumentum, the upper layer buff, composed of strongly fimbriate cup-shaped hairs, the lower compacted; petioles terete. Flowers 10–20, in a dense truss, 6–7-lobed, white with a purple basal blotch, ventricose-campanulate, nectar pouches lacking, 35–45 mm; stamens (10–)12–14; ovary densely tomentose. Flowering April-May. Royal Horticultural Society (1997).
Distribution Myanmar NE
Habitat c.3,350 m
RHS Hardiness Rating H5
Conservation status Vulnerable (VU)
R. preptum may be a hybrid of R. rex and R. coriaceum. Royal Horticultural Society (1997).