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FOC | Family List | FOC Vol. 14 | Apiaceae | Rhododendron

389. Rhododendron roxieanum Forrest ex W. W. Smith, Notes Roy. Bot. Gard. Edinburgh. 8: 344. 1915.

卷叶杜鹃 juan ye du juan

Shrubs, 1–3 m tall; branchlets short, stout and slightly flexuous, densely rufous or rust-red woolly-tomentose when young; bud scales persistent. Petiole ca. 10 mm, thickly woolly-tomentose; leaf blade thickly leathery, narrowly lanceolate to oblanceolate or linear, 3–10 × 0.5–3 cm; base cuneate, decurrent along petiole; margin strongly revolute; apex acute and with a stiff sharp point, or cucullate; abaxial surface with indumentum 2-layered, upper layer thick, rust-red to rufous, loose, woolly-tomentose, hairs branched, lower layer thin, compacted; adaxial surface shiny, slightly rugulose, glabrous except for groove of midrib. Inflorescence racemose-umbellate, 10–15-flowered; rachis ca. 10 mm, rusty red-tomentose. Pedicel 1–1.5 cm; calyx lobes 5, 0.5–1 mm, densely rust-red branched-tomentose and short-glandular-hairy; corolla campanulate to funnel-campanulate, white to white tinged pink, with copious purple-red spots on corolla-tube and on upper lobes, 2–3.5 cm, lobes 5; stamens 10, unequal, filaments densely puberulent in lower 1/2; ovary ca. 5 mm, densely rusty red-tomentose, sometimes mixed with short-stalked glands; style glabrous, stigma discoid. Capsule oblong cylindric, ca. 18 × 5 mm. Fl. Jun–Jul, fr. Aug–Oct.

Coniferous forests, Rhododendron thickets, mountains, slopes; 2600–4300 m. S Gansu, SW Shaanxi, SW Sichuan, SE Xizang, NW Yunnan.

The extensive synonymy reflects the considerable variation in this species, especially with respect to the leaves. This variation may be in part due to hybridization in the field. In particular, var. cucullatum appears to be intermediate between the more extreme var. oreonastes and Rhododendron proteoides. However, relatively uniform populations of var. cucullatum occur in W Yunnan.


1 Leaf blade linear, 0.5–1 cm wide; corolla 2–2.5 cm.   389c var. oreonastes
+ Leaf blade narrowly lanceolate or oblanceolate, 1.3–2 cm wide; corolla 3–3.5 cm.   (2)
       
2 (1) Leaf blade narrowly lanceolate, 6–10 × 1.3–2 cm; apex acute with a stiff sharp point.   389a var. roxieanum
+ Leaf blade oblanceolate, 3–8 × 2–3 cm; apex acute to cucullate.   389b var. cucullatum

Lower Taxa


 

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