香丝草 xiang si cao

Conyza ambigua Candolle; C. bonariensis (Linnaeus) Cronquist; C. crispa (Pourret) Ruprecht; C. leucodasys Miquel; Erigeron crispus Pourret; E. linifolius Willdenow; Leptilon bonariense (Linnaeus) Small; Marsea bonariensis (Linnaeus) V. M. Badillo.

Herbs, annual or biennial, [10-]20-50[-150] cm tall; roots fusiform, fibrous rooted. Stems erect or ascending, thin, often branched above middle, densely leafy, densely strigose, sparsely hirsute. Leaves: basal withered at anthesis, lower cauline long petiolate, blade oblanceolate or oblong-lanceolate, 3-5[-8] × 0.3-1[-2.5] cm, surfaces densely strigose or hispidulous, base attenuate, margin usually coarsely serrate or pinnatilobed, sometimes entire, apex acute or obtuse, mid and upper shortly petiolate or sessile, blade narrowly lanceolate or linear, [1-]3-7 × 0.2-0.5[-1] cm, margin of mid dentate, margin of upper entire. Capitula 3-10 mm in diam., numerous, in racemiform or racemose-paniculiform synflorescences; peduncles 10-15 mm. Involucre urceolate, ca. 5 × 8 mm; phyllaries 2- or 3-seriate, linear, abaxially densely gray-white scabrous, apex acute, outer ones slightly short or ca. 1/2 as long as inner, inner ones ca. 4 × 0.7 mm, margin scarious. Ray florets 65-150 or more, white, 3-3.5 mm, elaminate or 3- or 4-denticulate at apex; disk florets ca. 3 mm, tube sparsely puberulent. Achenes linear-lanceoloid, compressed, ca. 1.5 mm, sparsely strigillose [or glabrous]. Pappus reddish, sordid, or tawny, 3-4 mm. Fl. May-Oct.

Field margins, grassy slopes, roadsides; sea level to 3100 m. Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [native to South America; widely distributed as a weed in tropical and subtropical regions worldwide].