杯鞘石斛（植物分类学报）
Dendrobium gratiosissimum Rchb. f. in Bot. Ztg. 23: 99. 1865; Hook. f., Fl. Brit. Ind. 5: 743. 1890; Kraenzl. in Engler, Pflanzenr. 45 (IV. 50, II. B. 21): 46. 1910; Seidenf. in Opera Bot. 83: 58, fig. 31. 1985; Averyanov, Vasc. Pl. Syn. Vietnam. Fl. 1: 73. 1990; Seidenf., l. c. 114: 230. 1992; Averyanov, Iden. Guide Vietnam. Orch.: 196. 1994; Z. H. Tsi et S. C. Chen in Acta Phytotax. Sin. 33 (3): 291. 1995; Z. H. Tsi, S. C. Chen et K. Mori, Wild Orch. China: 78, pl. 88. 1997; 中国兰花全书: 164. 图6-11 (6). 1998.
Epiphytic on tree trunks in open forests; 800-1700 m. S Yunnan [NE India, Laos, Myanmar, N Thailand, Vietnam].
This species is physically resembling Dendrobium wardianum Warner, whereas the flower color is similar to that of D. devonianum Paxt., except that the former has smaller flowers and bracts, with discontinuous pale yellow semilunar patches on the lips ; different from the latter, the stem is thick, the node is slightly enlarged, the petal is full, and the lip edge has no tassel.
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Stems pendulous, cylindric, to 50 cm, ca. 5 mm in diam., fleshy, with many swollen nodes, upper part ± upcurved, internodes 2-2.5 cm, pale yellow when dry. |
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Leaves oblong, 8-11 × 1.5-1.8(or more) cm, leathery, base with clasping sheath, apex slightly obtuse and hooked on one side; leaf sheath papery when dry, sheath mouth open cupular. |
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Inflorescence on old leafless stems, 1- or 2-flowered; peduncle 3-5 mm; basal sheaths 2 or 3, pale white when dry, broadly ovate, 3-5 mm, papery, obtuse; floral bracts broadly ovate, 7-10 mm, papery, apex obtuse. Pedicel and ovary pale purple, ca. 2 cm. Flowers fragrant, spreading, papery; sepals and petals white with pale purple tips, lip with many purplish red stripes on each side, disk with a pale yellow transverse semilunar central blotch, column white, front side with purple stripes, anther cap white. Dorsal sepal ovate-lanceolate, 23-25 × 7-8(or more) mm, 7-veined, apex acute or slightly obtuse; lateral sepals suborbicular, equal in size, 7-veined, base oblique, apex acute; mentum subglobose, small, ca. 3 mm. Petals obliquely ovate, 23-25 × 13-14 mm, main veins 5, secondary veins many, base contracted into a short claw, margin entire, apex obtuse; lip nearly broadly obovate, ca. 23 × 20 mm, adaxially densely barbellate, base cuneate, margin ciliate, apex rounded. Column ca. 4 mm; anther cap subconic, densely finely papillate, front margin irregularly dentate. Capsule ovoid, ca. 3 × 1.3-1.6 cm. Flowering April-May. |
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Capsule ovoid, ca. 3 × 1.3-1.6 cm.
Fruiting period : June-July.
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