XANTHIUM

Xanthium L., Sp. Pl. 2: 987. 1753; Gen. Pl. 5: 424. 1754; Hook. f., Fl. Brit. Ind. 3: 303. 1882; Fl. China @ eFloras.org 20-21: 875; Fl. North Amer. @ eFloras.org 21: 19.

Annuals. Stem erect, branched. Leaves cauline, mostly alternate, petiolate, leaf blade lanceolate, linear, ovate, orbicular-deltate or suborbicular, often palmately or pinnately lobed, both surfaces hirtellous or +/- strigose, usually gland-dotted, ultimate margin entire or toothed. Capitula either male (distal) or female (proximal) in racemes or spikes or borne singly (in axils). Male capitula: Involucres saucer-shaped; phyllaries in 1-2 series, free to bases. Receptacle conical to columnar, paleate. Paleae spathulate to cuneiform or linear, membranous apically villous or hirtellous. Male florets 20-50. Corolla white, funnelform, lobes 5, erect or reflexed. Anthers 5, free or weakly coherent, filaments connate. Female capitula: Involucres +/- ellipsoid, 2-5 mm in diameter at anthesis. Phyllaries in 6-12 series, outer 5-8 phyllaries distinct, (remainders sometimes interpreted as paleae) inner many proximally connate, their distinct tips mostly +/- hooked (distal 1-3, mostly 2 usually longer and stouter, hooked or not), whole becoming a hard, prickly perigynium (a bur). Female florets 2. Corolla absent. Cypselae black, fusiform, enclosed in obovoid to ellipsoid, hard, prickly, 2-chambered burs; pappus absent.

6 species

Xanthium strumarium

Xanthium strumarium L., Sp. Pl. 2: 987. 1753; Hook. f., Fl. Brit. Ind. 3: 303 1882; Collett, Fl. Siml. ed. 2: 261. 1921 (Reprint 1980); Sharma & Kachroo, Fl. Jammu (Illustr.) 2: t. 131.1983; X. indicum Koen. in Roxb. Fl. Ind. (ed. Carey) 3: 601. 1832; Chowdhery in Hajra et al. Fl. Ind. 12: 427. f. 123. 1995; Kaur & Sharma, Fl. Sirmaur 401. 2004; Singh & Sharma, Fl. Chamba Dist. 438. 2006; Fl. China @ eFloras.org 20- 21: 864; Fl. North Amer. @ eFloras.org 21: 180.

Erect, branched, aromatic, annual herb, up to 2 m tall. Stem furrowed, strigose, purple-spotted; nodal spines absent. Leaves alternate, petiolate; petiole up to 15 cm long, pubescent-strigose, purple-tinged, adaxially with shallow groove; leaf blade 9-18 (-25) cm long and +/- broad, triangular or suborbicular, acute, acuminate, obtuse or rounded, palmately 3 (to 5) or obsoletely 3-lobed, margin irregularly coarsely dentate or toothed, cordate to broadly cuneate at base, gland-dotted, both surfaces densely scabrid. Capitula 1-sexual, male and female on the same plant, combined in axillary or terminal clusters Male capitula: Uppermost, globose, 7-8 mm in diameter, shortly stalked, stalk 3-4 mm long, pubescent. Phyllaries (involucral bracts) few, in 1 series, oblong-lanceolate, 2-3 mm long, acute, ciliate, spreading. Receptacle cylindric. Male florets: Many, up to 50, crowded, each enclosed in a translucent palea, 2-3 mm long, spathulate, acuminate, hairy at top or margin ciliate apically. Pappus 0. Corolla white or green, tubular, ca. 2.5 mm long, 5-toothed, teeth erect, triangular, ca. 0.5 mm long. Stamens 5, filaments connate, ca. 1 mm long; anthers linear, ca. 1.5 mm long, free or connate weakly at apex. Female capitula: Ovoid, ca. 1.2 cm long. Phyllaries (Involucral bracts) 2-seriate; outer few, 3-4 mm long, narrowly lanceolate, acute, hairy; inner many in one series, narrow, united, covered with hooked bristles and terminating in 2 strong hooked beaks. Female florets 2. Pappus and corolla none. Style branches long, thread-like, protruding from between the beaks near apex. Cypselae 7-8 mm long, broadly ellipsoid or obovoid, thick, ribbed, flattened, brown, enclosed in the hardened phyllaries (perigynium / bur), ca. 1.4 cm long, black with 2 long beaks, reaching up to 2-2.8 cm in length.

Flowering and Fruiting: July to October
Common Names: Common Cocklebur, Broad Bur, Burdock, Datura, Clotbur, Rough Cocklebur; Chhota Datura, Ghaghra (Hindi)