翼子裸柱菊 yi zi luo zhu ju

Gymnostyles pterosperma Jussieu, Ann. Mus. Natl. Hist. Nat. 4: 262. 1804.

Stems decumbent, not rooting adventitiously, branches ascending, pilose. Leaves in basal rosettes, alternate, spatulate in outline, 1.5-5 cm overall; petiole widened below synflorescences; leaf blade tripinnatifid to tripinnate, both surfaces pilose. Capitula axillary, scattered along stem, sessile, to 5 mm in diam. Involucres hemispheric, ca. 3 × 5 mm; phyllaries in ca. 2 rows, subequal, oblong to lanceolate, 4-4.5 × 1.5-2 mm, herbaceous, abaxially pilose. Marginal female florets 13-15, in several rows, corolla absent, styles forked, persistent; disk florets 5 or 6, corolla greenish, tubular, 1.6-1.8 mm, apex 4-lobed; style capitate. Achenes obovate, ca. 2 × 3 mm, dorsiventrally flattened, glabrous, with thin, flat lateral wings indented below middle into a small basal lobe and larger upper one, apex with persistent, spinelike style, often with additional incurved spines on shoulders of upper lobes.

Naturalized in parks and gardens. N Taiwan [native to South America].

Soliva pterosperma can be a noxious weed of lawns, readily distributed by the spiny infructescences. Webb (New Zealand J. Bot. 24: 665-669. 1986) suggested that it might not be separable from S. sessilis Ruiz & Pavon.