生活型

herb

形態特徵

• Annual ascending herbs, to 120 cm tall; stems branched, angled, armed with recurved prickles, usually producing fibrous roots at lower nodes.
• Leaves broadly lanceolate, 2.5–4.5 cm long, 0.7–1.5 cm wide, apex acute, base sagittate, both surfaces glabrous, beneath midvein retrorsely prickly; petioles 0.5–2 cm long, retrorsely prickly along the angles; ocreae tubular, 0.5–1 cm long, apex oblique, glabrous, upper margins eciliate.
• Inflorescences 2–3-flowered fascicles in head-like racemes, terminal, densely flowered; peduncles retrorsely prickly, 4–10 cm long; bracts lanceolate, glabrous, apex acuminate, upper margins eciliate. Flowers white with purple tinge at the perianth-segment tip; pedicels included; perianth segments 5, elliptic, ca. 3 mm long, apex obtuse; stamens 8; styles 3-cleft, included; nectaries present.
• Achenes brown to dark brown, trigonous, smooth, slightly shining, 2.5–3 mm long.

分布

• 台灣 : at low to middle altitudes, in wet grassy places and margins of swamps.
• 世界 : North America, India, China (SW, C, E, N & NE), Mongolia, E Siberia, Korea and Japan.

引證標本

ILAN: Yuanyanghu, Kuo 149.

參考文獻

• LIU, HO-YIH, Flora of Taiwan, second edition 2: 310. 1996.  (Fl. Taiwan 2nd edit.)