Description :

• Annual or perennial herbs; stems simple or branched, erect, sometimes creeping or diffuse, often juicy, translucent and turgescent, without stinging hairs; plants monoecious or dioecious by abortion
• Leaves opposite, pairs equal or very unequal, entire or dentate, petiolate, with linear cystoliths; stipules intrapetiolar, completely connate
• Inflorescences axillary cymes, either dense and head-like or lax and paniculately branched, or flowers solitary; bracts small, rarely few and larger, deltate to linear
• Flowers unisexual, male and female flowers in same cyme
• Male flowers : tepals (2-)4, concave, subvalvate, sometimes connate into a truncate cup, often mucronate or appendaged on back; stamens as many as tepals; rudimentary ovary conical or oblong
• Female flowers : tepals 3, equal, or sometimes 1 tepal enlarged and gibbous or hood-like; staminodes 3, opposite tepals, scale-like, minute or inconspicuous, under tension and ejecting mature achene; ovary straight; stigma sessile, composed of a dense tuft of short hairs, deciduous
• Achene sessile, laterally compressed, slightly oblique, ovate to orbicular, ± smooth, free from perianth at maturity, not or only partly enclosed by hood-like tepal
• Seed with thin coat; embryo with large cotyledons
• x = 10, 12, 13 (polyploidy)

Nomenclature:

• Pilea Lindl.
  • Lindley: t. 4 (1821) name conserved
  • Endlicher: 284 (1837)
  • Weddell: 172, t. 6. C 7 & 8 (1856)
  • Weddell: 104 (1869)
  • Bentham: 384 (1880)
  • Engler: 108 (1888)
  • Rendle: 269 (1917)
  • Brown: 549 (1925)
  • Ball: 68 (1964)
  • Friis: 25 (1989a)
  • Friis: 557 (1989b)
  • Friis: 96 (1991)
  • Friis: 622 (1993)

Distribution & Notes:

• Global : Species ± 250, almost pantropical in distribution and in most subtropical regions with exception of Australia and New Zealand
• Southern Africa : Species 2: Pilea rivularis Wedd. indigenous in the Northern Province and * P. microphylla (L.) Liebm., a species with very small, 1-8 mm long, entire leaves, a native of tropical America, is cultivated as an ornamental garden plant or occurs as a garden weed, e.g. in KwaZulu-Natal