生活型

herb

形態特徵

• Small annual herbs. Stems decumbent, well branched, branches ascending, pilose.
• Leaves alternate, tripinnatifid to tripinnate, 1.5–5 cm long, pilose on both surfaces, petiole widened beneath flower heads.
• Heads solitary in leaf axils, sessile, ca. 3 mm long, 5 mm across, scattered along stem. Involucre hemispheric, bracts ca. 2 series, subequal, herbaceous, greenish, oblong to lanceolate, pilose on adaxial surface, entire, margins ciliolate, 4–4.5×1.5–2 mm. Outer florets 13–15, in several rows, style bifurcate at tip, 1 mm long. Central florets 5–6; corolla greenish, tubular, 1.6–1.8 mm long, 4-lobed at apex; style capitate, not branched at tip; stamens 4.
• Achenes ca. 2×3 mm, minutely pubescent, with thin planar wings, wings indented below middle resulting in a large upper lobe and a smaller basal lobe; styles becoming hard at maturity of achene, persistent, spinose, often with an additional incurved spine on shoulder of each upper lobe.

分布

• 台灣 : <i>S. pterosperma</i> has become fully naturalized in lawns of university campuses and city parks in northern Taiwan within the past decade. It is a particularly noxious weed in lawns, because of the abundant prickly infructescences.
• 世界 : A native of South America.

引證標本

TAIPEI: Natl. Taiwan Univ., Peng 14818; Yangmingshan, Peng 13985. TAOYUAN: Tayuan, Chiang-kaishek International Airport, Peng 17111.

參考文獻

• PENG, Ching-I & CHUNG, Kuo-Fang; LI, Hui-Lin, Flora of Taiwan, second edition 4: 1068. 1998.  (Fl. Taiwan 2nd edit.)