小半圆叶杜鹃 xiao ban yuan ye du juan

Rhododendron lopsangianum Cowan, Notes Roy. Bot. Gard. Edinburgh 19: 250. 1937; R. thomsonii var. lopsangianum (Cowan) T. L. Ming.

Leaf blade oblong-elliptic to ovate, 3–5 × 2–4 cm; abaxial surface sometimes sparsely hairy. Calyx 2–3 mm; ovary densely shortly glandular-hairy. Fl. May.

Thickets, rocky slopes; ca. 3800 m. S Xizang.

Rhododendron thomsonii var. pallidum Cowan (Notes Roy. Bot. Gard. Edinburgh 19: 253. 1937), described from Xizang, is thought to be a hybrid between subsp. lopsangianum and R. campylocarpum. It differs from subsp. lopsangianum in its relatively short calyx (2–8 mm), pink corolla, and glandular ovary.