Description:

• Annual or perennial herbs, sometimes subshrubs, rarely shrubs, usually hairy
• Leaves alternate, rarely subopposite, sessile or petiolate, entire or denticulate
• Flowers usually small, many, sessile, in unilateral, terminal or pseudoaxillary helicoid cymes with cymes simple or peduncle dichotomously branched to give a pair of cymes or flowers solitary at apices of leafy branches; bracts present or 0
• Calyx with a short tube; 5-lobed, lobes lanceolate or linear
• Corolla white, cream, yellow or orange yellow; tube usually cylindric, glabrous or hairy, throat often pubescent; lobes 5, variably shorter than tube, spreading
• Disc present or 0
• Stamens arising on corolla tube, included; filaments very short
• Ovary completely or incompletely 4- or 5-locular with a single, pendulous ovule in each locule; gynobase flat; anthers elliptic-oblong or lanceolate, sometimes pubescent at apices; style terminal, undivided, included; stigma conical at apex, with a broad ring at base of cone
• Fruit dry or somewhat fleshy, usually with 4 distinct 1-seeded nutlets, or nutlets cohering in pairs or reduced to 1 nutlet by abortion; nutlets with outer surface variable
• x = 13, 8 (7) (aneuploids, high polyploidy)

Nomenclature:

• Heliotropium L.
  • Linnaeus: 140 (1753)
  • Linnaeus: 63 (1754)
  • Candolle: 532 (1845)
  • Bentham: 843 (1876)
  • Boissier: 125 (1879)
  • Gürke: 90 (1897)
  • Wright: 7 (1904)
  • Friedrich-Holzhammer: 1 (1967)
  • Taton: 28 (1971)
  • Martins: 83 (1990)
  • Al-Shehbaz: 74 (1991)
  • Nowicke & Miller: 29 (1991)
  • Verdcourt: 50 (1991)
  • Riedl: 99 (1997)

Distribution & Notes:

• Global: Species ± 250, in tropical to warm, temperate regions, particularly in ± arid areas
• Southern Africa: Species 20, widespread but not recorded from Lesotho and Western Cape