Rhododendron preptum I. B. Balf. & Forrest

Rhododendron preptum is a doubtful species and may be a hybrid of R. arizelum and/or R. coriaceum. It is known only from two wild-collected specimens.

Shrubs or small trees, 5–7 m tall; older branches glabrous; branchlets stout, usually 8–10 mm in diam.; young shoots grayish to brownish tomentose. Petiole terete, 15–20 mm, tomentose, glabrescent; leaf blade leathery, obovate-elliptic, 11–16 × 4–7 cm; base cuneate; apex obtuse or rounded, apiculate; abaxial surface with pale brown, 2-layered indumentum, upper layer of cup-shaped slightly fimbriate hairs, lower layer thin, compacted; adaxial surface glabrous; midrib prominent abaxially, grooved adaxially; lateral veins 13–15-paired, prominent abaxially. Inflorescence ca. 20-flowered; rachis stout, ca. 20 mm, slightly tomentose. Pedicel ca. 2 cm, brown-tomentose; calyx saucer-shaped; teeth short, ca. 1 mm, with similar hairs; corolla obliquely campanulate, white (in cultivation) or perhaps creamy-white, with crimson basal blotch, ca. 3.5 cm, lobes 8, orbicular, ca. 1 × 1.5 cm; stamens 16, 1.5–2.5 cm, filaments pubescent at base; ovary conoid, ca. 7 mm, densely brown-tomentose; style ca. 2.5 cm, glabrous, stigma swollen. Capsule not known. Fl. May.

SW Yunnan [NE Myanmar].

Mixed forests, Rhododendron thickets; 3200–3300 m.