Description :

• Small trees or shrubs; trunk smooth, or with peeling papery bark, usually swollen at base; branches many, stiff, grey, ascending, rapidly tapering, with spinous branchlets; usually with mucilage glands, hairs sometimes stellate on young stems and other parts
• Leaves deciduous, obovate and entire, petiolate and alternate on long shoots, almost sessile and apparently fascicled on abbreviated branches in axils of spines (modified petioles)
• Flowers large, in terminal or subterminal, few-flowered, short, raceme-like inflorescences; white, cream, pink or yellow, tube often dark-coloured; sweet-scented
• Calyx much shorter than corolla tube, oblique
• Corolla : tube long, slightly curved, cylindrical, usually with a gibbosity to long spur near base; limb sub-bilabiate, spreading to reflexed; lobes subequal, elliptic or suborbicular, entire
• Stamens subequal, arising near throat of corolla tube, included; filaments broadly linear, shorter than anthers; thecae parallel; staminodes 0
• Nectary fused with base of ovary, oblique and posteriorly gibbous
• Ovary 2-locular; locules divided nearly to apex by a false septum; ovules many, in 1 row in each compartment; style linear, exserted; stigma of 2 ovate, membranous lobes
• Fruit a rigid, woody, obovate to oblong capsule, laterally compressed, loculicidal from apex to base
• Seeds large, subcircular to transversely oblong, compressed, with a broad, membranous, marginal wing; testa subleathery

Nomenclature:

• Sesamothamnus Welw.
  • Welwitsch: 49, t. 18 (1869)
  • Stapf: 567 (1906)
  • Bruce: 417 (1953)
  • Ihlenfeldt: 43, t. 7 (1967a)
  • Ihlenfeldt: 593 (1967b)
  • Merxmüller & Schreiber: 8 (1968)
  • Codd: t. 1640 (1972)
  • Ihlenfeldt: 87 (1988)
  • Ihlenfeldt: 1063 (1994)
• Sigmatosiphon Engl.
  • Engler: 150 (1894)
  • Bruce: 418 (1953)

Distribution & Notes:

• Global : Species ± 5, Africa
• Southern Africa : Species 2 or 3, N Namibia, Botswana, Messina (Northern Province) to Rustenburg (North-West), plus northern Kruger National Park (Northern Province) and Burgersfort area (N Mpumalanga); usually on calcareous soils