Xanthium L.

Herbs, annual, hispid-pubescent or glabrescent, armed or unarimed. Leaves alternate, entire or variously lobed, coarsely dentate, petiolate. Heads solitary or glomerate, terminal or axillary, unisexual. Male heads many flowered, nearly globose, subsessile, borne at the apices of branches. Involucre 1-rowed. Female ones near the base of the shoot, ovoid, 2-locular, each locule containing one flower. Involucral bracts in 2 rows; outer small, free, inner connate, coriaceous, prickly, ending in 2 beaks; prickles straight orhooked. Corolla of male florets greenish, tubular, 5-toothed. Filaments united; anthers free. Corolla of female florets absent. Stylar branches exserted through a hole on inside of each beak near the apex. Achenes 2 in each head, included in the hardened, spiny involucre at maturity. Pappus absent.

Cosmpolitan; ca 70 species, 3 in India.

KEY TO THE SPECIES

1a. Leaves green above, white beneath; Stems bearing yellow spines

3. Xanthium spinosum

b. Leaves green on both surfaces; stems without spines

2

2a. Fruiting involucre pale-green, covered with hooked bristles, devoid of glands or hairs; apical beaks divergent

1. Xanthium indicum

b. Fruiting involucre greyish-green to red-brown, covered with hairs and glands; apical beaks straight or incurved

2. Xanthium pungens

List of Lower Taxa