白花线柱兰 bai hua xian zhu lan

Hetaeria parvifolia Ridley, J. Straits Branch Roy. Asiat. Soc. 39: 87. 1903; Adenostylis benguetensis Ames; Zeuxine benguetensis (Ames) Ames; Z. boninensis Tuyama; Z. gracilis (Breda) Blume var. sakagutii (Tuyama) Hashimoto; Z. gracilis var. tenuifolia (Tuyama) T. Hashimoto; Z. leucochila Schlechter; Z. sakagutii Tuyama; Z. shuishiehensis S. S. Ying; Z. tenuifolia Tuyama; Z. tonkinensis Gagnepain.

Plants 15-22 cm tall, slender. Rhizome elongate. Stem erect, pale purplish brown, 3-6-leaved. Leaves cauline, widely spaced, withered or pendulous at anthesis, pale green, ovate to elliptic, 2-4(-6) × 1.2-2 cm, apex obtuse to acute; petiole-like base 1-1.5 cm including tubular sheath, margin sometimes ciliate. Inflorescence 10-20 cm, with 2 or 3 sterile bracts, pubescent; rachis 2-7.5 cm, with 3 to more than 10 laxly to subdensely arranged flowers; floral bracts pale red, ovate-lanceolate, 4-7 mm, shorter than ovary, pubescent abaxially and on margin, apex long acuminate. Flowers resupinate, small; ovary and pedicel fusiform, 6-9 mm, puberulent. Sepals dark green to purple-brown, sparsely puberulent; dorsal sepal ovate-lanceolate to ovate, 3.8-4.5 × 2-2.8 mm, 1-veined, apex acute; lateral sepals weakly to widely spreading, oblong-ovate, slightly oblique, 3.8-4.5 × 1.5-2 mm, 1-veined, apex acute to obtuse. Petals white, suboblanceolate-oblong, oblique, 4-4.5 × 1.2-1.3 mm, 1-veined, base attenuate, apex subobtuse; lip white or pale yellow, T-shaped, 3.5-5 mm, 3-partite; hypochile saccate, containing 2 subulate, hooked calli; mesochile ca. 1 mm, margin involute toward apex; epichile transversely oblong, ca. 1 × 3-4 mm, composed of 2 lobes diverging at right angles to axis of lip, often with a small mucro at apex between lobes; lobes suboblong, 1.5-2 × 0.8-1.2 mm, apical margin entire or sometimes irregularly denticulate. Column ca. 2 mm; wings much reduced and indistinct; anther ovoid-lanceolate, ca. 1.5 mm; rostellum arms linear, ca. 0.8 mm. Fl. Feb-Aug. 2n = 20.

Damp places, rocky soils in forests, mountain slopes; 200-1700 m. Hainan, Hong Kong, Taiwan, S and SW Yunnan [Cambodia, Japan, Laos, Malaysia, Myanmar, Philippines, Thailand, Vietnam].

This is a widespread and variable species in need of critical review. Reassessment of type material for certain synonyms placed here may reveal that they represent distinct species. The Japanese names are tentatively considered conspecific, following Garay and Sweet (Orchids S. Ryukyu Islands, 83-85. 1974).