刺苍耳 ci cang er

Acanthoxanthium spinosum (Linnaeus) Fourreau; Xanthium cloessplateaum D. Z. Ma; X. spinosum var. inerme Bel.

Herbs, annual, 10-60(-120) cm; nodal spines usually in pairs, simple or 2- or 3-partite, 15-30 mm. Petiole 1-15(-25) mm; leaf blade ± ovate to lanceolate or lanceolate-linear, 4-8(-12) × 1-3(-5) cm, often pinnately 3(-7)-lobed, abaxially gray to white, densely strigose. Burs 10-12(-15) mm. Fl. Jul-Oct. 2n = 36.

Damp or seasonally wet alkaline soils, wastelands, margins of agricultural land. Beijing, Henan [native to North and South America].

The synonymy of Xanthium spinosum is far more extensive than is indicated here. Xanthium ambrosioides Hooker & Arnott is sometimes included within the synonymy of this species. It is, however, a very distinctive taxon from Argentina (Patagonia) that should perhaps be recognized as a separate species.