小蓬草 xiao peng cao

Conyza canadensis (Linnaeus) Cronquist; Conyzella canadensis (Linnaeus) Ruprecht; Leptilon canadense (Linnaeus) Britton; Marsea canadensis (Linnaeus) V. M. Badillo.

Herbs, annual, 50-100 cm tall or more; root fusiform, fibrous rooted. Stems erect, sparsely hirsute, branched above, densely leafy. Leaves: basal withered at anthesis, lower petiolate, oblanceolate, [2-]6-10 × [0.4-]1-1.5 cm, surfaces or only adaxial sparsely pilose, base attenuate, margin sparsely serrate or entire, apex acute or acuminate; mid and upper subsessile or sessile, blade linear-lanceolate or linear, smaller, margin entire or rarely 1- or 2-toothed. Capitula 3-4 mm in diam., numerous, in terminal, large paniculiform synflorescences; peduncles slender, 5-10 mm. Involucre subcylindric, 2.5-4 mm; phyllaries 2- or 3-seriate, greenish, abaxially sparsely strigose [or glabrous], linear-lanceolate or linear, acuminate, outer ca. 1/2 as long as inner, inner 3-3.5 × ca. 0.3 mm, margin scarious, glabrous. Ray florets 20-30(-45), white, 2.5-3.5 mm, lamina slightly longer than disk floret, apex 2-denticulate; disk florets 8-30, yellowish, 2.5-3 mm, tube sparsely puberulent, lobes 4 or 5. Achenes linear-lanceoloid, compressed, 1-1.5 mm, sparsely strigillose. Pappus 1-seriate, dirty white, bristles 15-25, 2.5-3 mm. Fl. May-Sep.

Common weed of open places, field margins, roadsides, dry streamsides; sea level to 3000 m. Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan, Zhejiang [native to North America].