叉脊天麻 cha ji tian ma

Plants 2-5 cm tall. Rhizome cylindric, 5-9 cm, 0.5-0.8 cm in diam., with deltoid sheaths at nodes, sparsely pubescent. Peduncle dark brown, to ca. 4 cm, with several short tubular sheaths toward base; rachis 1-1.5 cm, densely 1-4-flowered; floral bracts broadly oblong-ovate, 5-7 mm, shorter than ovary, apex acuminate. Flowers suberect or spreading, resupinate, yellowish brown, 15-18 mm in diam.; pedicel and ovary 8-10 mm, shortly papillate; pedicel elongating in fruit. Perianth tube campanulate, outer surface verrucose; free portion of sepals spreading, broadly ovate, 4.5-6 × 5-6.3 mm, margin entire or crisped, apex obtuse; free portion of petals spreading, orbicular to broadly ovate, 3-3.5 × 3-3.5 mm, margin entire or crisped, apex obtuse; lip 3-lobed, orange-brown at base, tinged pale cream-brown toward apex, deltoid-ovate, 5-6 × 5.5-6.5 mm, base clawed; lateral lobes suborbicular to deltoid, 3.2-3.5 × 4.8-5 mm, apex obtuse to acute; mid-lobe oblong, 2-2.1 × ca. 1 mm, apex obtuse-truncate; claw quadrate or broadly obovate, 2.5-2.8 mm, with a pair of globose, papillose calli; disk papillose on lateral lobes, with a central fleshy keel that forks below mid-lobe into 2 shallow lamellae. Column 4-5 mm; column wings truncate, incurved; anther ovoid, 1.3-1.5 mm; column foot prominent, with a pair of rounded calli where it meets base of lip. Capsule cylindric. Fl. Mar.

Evergreen forests; 300-400 m. N Taiwan [Japan (Ryukyu Islands)].