生活型

herb

形態特徵

• Perennial herbs, tufted, 20-100 cm tall, rhizomes short, brown; roots fibrous, reddish brown. Culms trigonous, scabrous, sparsely with retrorse prickles, dark green, 2-3 mm wide.
• Leaves 3-5, 10-60 cm long, 2-6 mm wide, blades elongated linear,with antrorse prickles on distal margins, basally scattered with transverse septa between the nerves, V-shaped; sheath 3-10 cm long, whitish green, flushed with brown at base.
• Anthela compound to decompound, leafy bracts 3-9, very unequal, spreading or reflexed, 3-40 cm long, 1-6 mm wide, with antrorse prickles on margins, V-shaped; primary rays 6-10, very unequal, 0-5 cm long, scabrous with retrorse prickles. Spikelets 15-60 clustered in a globose head 1.5-2 cm across at apex of raylets, ovate to lanceolate-ovate, flattened, 2-7 mm long, 1.5-2 mm wide, densely 16-30 flowered; rachilla slightly zigzag.
• Glumes ovate, 1.4 mm long, 0.6 mm wide, 3-nerved, pale-green, the midrib green, apex mucronulate. Stamen 1, filaments 0.5 mm long, white, anthers yellow, 0.5 mm long, linear with a subulate appendage at apex. Styles pale-brown, 0.5 mm long, stigmas 3, 0.6 mm long, pale-brown, ovary yellowish green, trigonous, 0.6 mm long, 0.2 mm wide. Achenes 3-angled, narrowly ellipsoid, 0.8 mm long, 0.4 mm wide, slightly stipitate, acute and apiculate at apex, reddish brown, reticulate and papillae on surfaces.

分布

• 台灣 : It occurs in the lowlands of northern Taiwan as a weed distributed in sunny, wet, disturbed sites, in shallow water, on edges of streams and ponds.
• 世界 : probably of tropical American origin, but is now widespread from the southern United States and Mexico, through Central America, to the West Indies and South America.

引證標本

Taipei City: Taipei Botanical Garden, at pond margins, 10 Mar 2007, Weng 12 (NHU); near Bai-ling Park, on roadsides along Keelong River, 22 Nov 2008, Weng 132 (NHU). Taoyuan Co.: Guishan Hsiang, Fengshu Village, 28 Sep 2002, Chen 471 (TAIF). Miaoli Co.: Tunglo, 14 Jul 2001, Lin 315 (TAIF).

參考文獻

• Shih-Huei Chen, Shu-Huei Weng and Ming-Jou Wu, Taiwania 54(4): 399. 2009.