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Shrub or small tree, 2.5-9m; bark rough. Leaves 13.5-15 x 5.5-6.2cm, 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, 35-45mm; stamens (10-)12-14; ovary densely tomentose.
Distribution NE Burma.
RHS Hardiness H3-4a.
R. preptum may be a hybrid of R. rex and R. coriaceum.