Description:

• Annual or perennial herbs
• Leaves opposite, sessile or petiolate, simple to deeply and irregularly 2- or 3-pinnatisect; blade or segments linear to broadly ovate, entire, serrate-crenate, or variously incised
• Capitula radiate, occasionally ray florets 0, on long peduncles, solitary and terminal or arranged in lax corymbiform or paniculiform cymes
• Involucre campanulate or subhemispherical; bracts ± in 2 rows, outer herbaceous to coriaceous, inner one membranous to subcoriaceous
• Receptacle flat to conical
• Ray florets neuter, rarely female; corolla white, pink, crimson, orange or yellow, strap-shaped
• Disc florets bisexual, fertile; corolla yellow, narrowly cylindric below, expanded above, 5-lobed with lobes papillose
• Anthers obtuse or minutely sagittate at base; with ovate apical appendage
• Style swollen at base, terete; branches narrowly oblong, apex acute with subulate appendage, short sweeping hairs on outer face
• Cypselas 3- or 4-angled or dorsiventrally compressed, linear-oblong to broadly ovate, sometimes beaked
• Pappus of 2-4 awns, usually barbed
• x = 6, 8 (5, 11, 17, 23) (aneuploids, high polyploidy, B-chromosomes)

Nomenclature:

• Bidens L.
  • Linnaeus: 831 (1753)
  • Linnaeus: 362 (1754)
  • Candolle: 593 (1836)
  • Oliver & Hiern: 392 (1877)
  • Sherff: 1 (1937)
  • Phillips: 818 (1951)
  • Henderson & Anderson: 326, 328 (1966)
  • Hilliard: 316 (1977)
  • Mesfin: 43 (1984)
  • Mesfin: 437 (1993)
  • Karis & Ryding: 614 (1994)

Distribution & Notes:

• Global: Species 233, cosmopolitan
• Southern Africa: Species 6, 2 of them, *Bidens bipinnata L. and *B. pilosa L. are introduced, widespread, roadside weeds and noxious weeds of cultivation, absent from the Western Cape