13. Rhododendron subsect. Arborea (Tagg) Sleumer, Bot. Jahrb. Syst. 74: 545. 1949.
树形杜鹃亚组 shu xing du juan ya zu
Fang Mingyuan (方明渊); David F. Chamberlain
Rhododendron subser. Arborea Tagg in J. B. Stevenson, Sp. Rhodod. 12. 1930 ["Arboreum"].
Trees; bark rough; young shoots tomentose or floccose, glabrescent. Leaf blade elliptic to oblanceolate; abaxial surface densely spongy to compacted, white to fawn, tomentose, hairs dendroid sometimes with a floccose rufous upper layer. Inflorescence dense, 10–30-flowered. Calyx minute, 1–2 mm; corolla campanulate or tubular-campanulate, 5-lobed, pink to deep crimson, magenta or lilac, very rarely white, with nectar pouches; stamens 10; ovary densely tomentose, rarely glandular; style glabrous.
About four species: Bhutan, China, India, Kashmir, Myanmar, Nepal, Sikkim, Sri Lanka, Thailand, Vietnam; four species in China.
This is a subsection of uncertain affinities, though probably allied to R. subsect. Argyrophylla and, in particular, to R. denudatum.
