237. Rhododendron sinogrande I. B. Balfour & W. W. Smith, Notes Roy. Bot. Gard. Edinburgh. 9: 274. 1916. 凸尖杜鹃 tu jian du juan Rhododendron sinograndeCredit: Harvard University Herbaria Rhododendron sinogrande var. boreale Tagg & Forrest.Trees, 5–12 m tall; shoots stout, 1–1.5 cm in diam., thinly silvery-gray-tomentose. Petiole stout, 30–50 mm, with silvery appressed indumentum; leaf blade thickly leathery, oblong-elliptic to oblong-oblanceolate, 20–70 × 8–30 cm; base broadly cuneate or rounded; margin slightly revolute; apex rounded or obtuse and stiffly mucronate; abaxial surface silvery-gray to buff, indumentum compacted and agglutinated; adaxial surface glabrous; midrib prominent abaxially. Inflorescence racemose-umbellate, 15–20-flowered; rachis 30–60 mm. Pedicel stout, 3–5 cm, with a dense buff tomentum; calyx oblique; lobes 8(–10), ca. 2 mm, triangular, tomentose or glabrescent; corolla ventricose-campanulate, fleshy, creamy-white to pale yellow, 4.5–5.5 cm, with crimson nectar pouches at base inside; lobes 8(–10); stamens 18–20, unequal, filaments densely puberulent at base; ovary ca. 10 mm, densely pale brown-tomentose, eglandular; style glabrous, stigma large and discoid. Peduncle 6–6.5 cm. Capsule large and woody, cylindric, slightly curved, 40–70 × 14–17 mm, densely rusty-tomentose. Fl. Apr–May, fr. Aug–Oct.Coniferous forests in alpine regions, Rhododendron thickets; 2100–3600 m. SE Xizang, W Yunnan [NE Myanmar].【引自:Flora of China】
常绿乔木,高5-12米;幼枝粗壮,直径1-1.5厘米,被薄层银灰色毛被。叶大,厚革质,长圆状椭圆形或长圆状倒披针形,长20-70厘米,宽8-30厘米,先端圆或钝,具硬凸尖头,基部宽楔形或圆形,边缘略反卷,上面无毛,微有皱纹,中脉凹入或平坦,侧脉15-18对,凹入,下面具光泽,被银灰色至淡黄色粘结状紧贴的毛被,中脉极度凸起,侧脉显著;叶柄粗,长3-5厘米,被银灰色紧贴的毛被。顶生总状伞形花序或伞形花序,有花15-20朵,总轴长3-6厘米,被微绒毛,无腺体;花梗粗壮,长3-5厘米,密被淡黄色微绒毛;花萼小,偏斜,长约2毫米,8-10裂,裂片三角形,被微柔毛或近无毛;花冠宽钟形,偏斜,肉质,长4.5-5.5厘米,乳白色至淡黄色,里面基部具深红色蜜腺囊,8-10裂,裂片圆形,长约1.5厘米,宽2厘米,顶端微有缺刻;雄蕊8-20,不等长,长1.5-2.5厘米,花丝基部密被微柔毛,花药椭圆形,黄褐色,长3毫米;雌蕊稍短于花冠,长于雄蕊;子房圆锥形,长约1厘米,密被淡棕色绒毛,无腺体,花柱无毛,柱头大,盘状。蒴果大,木质,圆柱形,长4-7厘米,直径1.4-2.7厘米,密被锈色绒毛,略弯,果梗长6-6.5厘米。花期4-5月,果期8-10月。 【引自:中国植物志】