Description:

• Trees, shrubs, perennial or annual herbs
• Leaves paripinnate; extrafloral nectaries often present on leaf stalks or raceme axes or both, verruciform, claviform or phalloid, secretory surface convex
• Inflorescence a 1-many-flowered raceme, primitively axillary, often becoming corymbose-paniculate towards end of branchlets or rarely cauliflorous; bracteoles 0
• Petals 5, yellow, exceptionally white, either subiso- or strongly heteromorphic, vexillar one interior in bud
• Stamens 5-10, straight filaments shorter than or not over twice as long as basifixed anther, when less than 10 stamens fertile then whole set accrescent toward abaxial side of flower, adaxial ones dwindling to staminodes, perfect anthers either truncate, obliquely produced into a pollen cup, or beaked, lateral sutures glabrous, their dehiscence terminal by pore or short slit
• Pod terete, 4-angulate, turgid, or plano-compressed, sometimes winged lengthwise along either sutures or valves; valves varying from papery to coriaceous or ligneous, cavity often transversely septate, seeds 1- or rarely 2-seriate, oriented either transversely or basipetally; indehiscent or tardily dehiscent along ventral suture, or through both sutures, but valves never coiling
• Seeds not punctate
• x = 7 (can also be 14, polyploidy)

Nomenclature:

• Senna Mill.
  • Miller: [1280] (1754)
  • Irwin & Barneby: 105 (1981)

Distribution & Notes:

• Global: Species ± 240, circumtropical, most numerous in the Americas, well represented in Africa and Australia
• Southern Africa: 5 species indigenous, others have become naturalised