Xanthium spinosum L.

Erect annual, 10–100 cm tall. Stems sparsely to densely hairy above, becoming glabrous below, usually much-branched from base or above. Lvs sessile or shortly petiolate, with 1–2 axillary spines; spines stout, (2)–3–(4)-fid, (0.5)–1–3 cm long; lamina with scattered hairs on upper surface and dense white to grey tomentum on veins and lower surface, mostly narrow-ovate, entire or pinnately 3–(5)-fid, obtuse to cuneate at base, 2–10 cm long; segments narrowly ovate-lanceolate, lanceolate, or triangular; uppermost lvs often smaller, narrower and entire. ♂ capitula in terminal infls, with numerous florets; ♀ capitula solitary or clustered, in axils. Fruiting involucre sparsely to moderately clothed in short hairs, less hairy at maturity, 10–13 × 5–7 mm; prickles hooked, glabrous, 2–3 mm long; beaks 1–2, indistinct, 0.5–1 mm long.

[From: Webb et al. (1988) Flora of New Zealand. Volume 4.]

Flowering: Dec.–Apr.; Fruiting: Dec.–Jul.