536. Rhododendron obtusum (Lindley) Planchon, Fl. Serres Jard. Eur. 9: 80. 1853–1854. 1853.
钝叶杜鹃 dun ye du juan
Azalea obtusa Lindley, J. Hort. Soc. London 1: 152. 1846.
Low shrubs, 1(–4) m tall; branchlets slender, often pseudoverticillate, densely coarsely ferruginous-strigose. Leaves all similar. Petiole ca. 2 mm, coarsely gray-white-strigose; leaf blade membranous, elliptic to elliptic-ovate or oblong-oblanceolate to obovate, 1–2.5 × 0.4–1.2 cm; base broadly cuneate; margin ciliate; apex obtusely pointed or rounded, sometimes mucronate; both surfaces sparsely coarsely strigose, more conspicuously so along midrib. Inflorescence usually 2- or 3-flowered. Pedicel 0.4–0.8 cm, densely coarsely ferruginous-strigose, hairs flat; calyx lobes ovate, to 4 mm, coarsely strigose; corolla funnel-campanulate, red to pink or reddish, one lobe with dark flecks, ca. 1.5 × 2.5 cm; lobes oblong, ca. 1 × 0.5 cm, apex obtuse; stamens 5, ca. as long as corolla, filaments, glabrous; ovary densely coarsely brown-strigose; style ca. 2.5 cm, longer than stamens, glabrous. Capsule conical to broadly elliptic-ovoid, ca. 6 mm, densely coarsely ferruginous-strigose.
Cultivated in E and SE China [of cultivated origin].
There are many varieties and garden hybrids of this widely cultivated plant, the first form of which originated in Shanghai. It seems likely that Rhododendron obtusum was derived from a hybrid of the Japanese R. kiusianum Makino.