Xyris chinensis Malme; X. ridleyi Rendle.

Herbs tufted. Leaf sheath 1/5--1/4 as long as blade; leaf blade narrowly ensiform-linear, 9--15(--17) cm × 1.5--2 mm, smooth or minutely and transversely rugulose, nervose-striate, apex acute. Peduncle (15--)25--40(--50) cm × ca. 0.8 mm, subterete, smooth, basally subtended by a sheath. Spikes subglobose to obovoid, 5--7 mm, few flowered; basal bracts oblong-ovate, ca. 4 mm, indistinctly keeled, apex rounded and usually emarginate; median bracts obovate, ca. 5 × 3.5 mm, conchiform, not keeled, apex rounded and few lacerate-fimbriate. Lateral sepals free, subequilateral, linear to narrowly obovate, curved, 4.5--5 mm, less than 1 mm wide, margin few lacerate-fimbriate, keel narrow and entire at base and apex but central portion slightly wider and denticulate. Fl. Aug--Sep.

Swamps. Hong Kong [Cambodia, Indonesia, Malaysia, New Guinea, Thailand, Vietnam].