景洪石斛Dendrobium exile

　　中文名（Chinese Name）：景洪石斛
学名（Scientific Name）：Dendrobium exile Schltr.
英文名（English Common Name）：
别名（Chinese Common Name）：
异名（Synonym）：Aporum heterocaulon (Guillaumin) Rauschert  Ceraia exilis (Schltr.) M.A.Clem.  Dendrobium heterocaulon Guillaumin
科属（Family & Genus）：兰科（Orchidaceae）石斛属
形态特征（Description）：茎直立，细圆柱形，多少木质化，长达50厘米，粗约3毫米，上部常分枝，基部上方2-3个节间膨大呈纺锤形；膨大部分的茎肉质，长4.5厘米，粗约8毫米，具4个棱，幼时被浅白色的膜质鞘，老时赤褐色并且具光泽。叶通常互生于分枝的上部，直立，扁压状圆柱形，长2.5-6厘米，宽1.5-2.5毫米，先端锐尖，基部具革质鞘。花序减退为单朵花，侧生于分枝的顶端，白色，开展；花苞片卵形，长约2毫米，先端钝尖；花梗和子房纤细，长约1厘米；萼片和花瓣近披针形，先端长渐尖；中萼片长1.7厘米，宽约2.5毫米，具5条脉；侧萼片约等大于中萼片，基部歪斜与蕊柱足形成角状的萼囊；萼囊劲直，朝上，长约1厘米，末端急尖；花瓣长1.7厘米，宽1.5毫米，具3条脉；唇瓣基部楔形，中部以上3裂；侧裂片斜半卵状三角，内面具少数淡紫色斑点，先端钝，前端边缘波状；中裂片狭长圆形，先端急尖，边缘波状；唇盘黄色，被稀疏的长柔毛，从基部至先端纵贯3条龙骨脊；蕊柱长2毫米，蕊柱足近基部具1个胼胝体；药帽圆锥形。蒴果纺锤形，长4厘米，粗6毫米。花期10-11月，果期11-12月。
分布（Distribution）：产云南南部（景洪、勐腊）。生于海拔600-800米的疏林中树干上。越南、泰国也有。
用途（Use）：
引自中国植物志英文版：FOC Vol. 25 Page 369, 396
Dendrobium exile Schlechter, Repert. Spec. Nov. Regni Veg. 2: 85. 1906.
景洪石斛 jing hong shi hu | Orchidaceae  | Dendrobium
Ceraia exilis (Schlechter) M. A. Clements.
Stems erect, upper part branched, cylindric, to 50 cm, slender, ca. 3 mm in diam., 2 or 3 internodes above base dilated and fusiform; dilated portion of stems ca. 4.5 cm, ca. 8 mm in diam., fleshy, with 4 ribs, with pale white membranous sheaths when young, reddish brown and glossy when old. Leaves often alternate on upper part of branches, erect, terete, 2.5-6 × 1.5-2.5(or more) cm, base with leathery sheaths, apex acute. Inflorescence axillary on leafy older stems, 1-flowered, up to 4 flowers open at once per stem; floral bracts ovate, ca. 2 mm. Pedicel and ovary ca. 1 cm, slender. Flowers spreading, white, inner surface of lip lateral lobes with a few pale purple spots, disk yellow. Dorsal sepal sublanceolate, ca. 17 × 2.5 mm, 5-veined, long acuminate; lateral sepals similar to and ca. as large as dorsal sepal; mentum rigid, ca. 1 cm, acute. Petals similar to sepals, ca. 17 × 1.5 mm, 3-veined; lip cuneate at base, 3-lobed above middle; lateral lobes obliquely subovate-triangular, front margin undulate, apex obtuse; mid-lobe narrowly oblong, margin undulate, apex acute; disk sparsely villous, with 3 thick and stout keeled ridges from base to apex. Column ca. 2 mm, foot with a basal callus; anther cap conic. Capsule fusiform, ca. 4 × 0.6 cm.
Epiphytic on tree trunks in open forests; 600-800 m. S Yunnan (Jinghong, Mengla) [Thailand, Vietnam].