Description:

• Annual or rhizomatous perennial herbs, subshrubs, shrubs, sometimes small trees or climbers with soft wood, clear sap, often tough, fibrous bark, occasionally with stinging hairs, but also frequently with stiff nonstinging hairs, which may be curled or sharply hooked; cystoliths usually punctiform, elongated or linear in epidermal cells; plants monoecious or dioecious, or rarely polygamous
• Leaves alternate or opposite, sometimes anisophyllous, simple or 3-5(-7)-lobed, entire, serrate or dentate, usually with 3 subequal nerves from base reaching towards leaf apex, petiolate or sessile; stipules usually present, lateral or often intrapetiolar and connate
• Inflorescences axillary or terminal, extremely varied, mostly pedunculate, lax or condensed racemes, often with flowers in small cymose glomerules, or sessile and condensed cymes in leaf axils, partial inflorescences often subtended by involucral bracts
• Flowers unisexual or rarely bisexual, regular or (especially in female flowers) irregular, hypogynous, minute; perianth 1-whorled; tepals 1-5, or rarely female flowers naked, free or ± connate, imbricate or valvate, persistent; pedicel often articulated below perianth
• Male flowers usually pedicellate, white or green, with stamens as many as tepals and opposite them, free or connate in lower half, rarely completely fused and split along one side; filaments broadened at base and inflexed in bud, suddenly reflexing and ejecting pollen; anthers basifixed, dehiscing by longitudinal slits; rudimentary ovary frequently present
• Female flowers usually sessile, greenish or reddish, with 3-5 tepals, free or ± completely connate, often very unequal, often accrescent after pollination, rarely rudimentary or completely absent; staminodes, if present, rudimentary or scale-like and important for dispersal of fruit (ejecting achene when reflexing); ovary superior, unicarpellate, often oblique or asymmetrical, 1-locular, placentation basal; ovule solitary, erect, orthotropous, bitegmic, crassinucellate; style present or stigma sessile; stigma 1, capitate, penicillate, ligulate or filiform, linear
• Fruit a dry achene, sometimes enclosed by persistent, accrescent perianth which may become fleshy
• Seed with thin testa, not fused to endocarp; endosperm ± copious, thin, oily or starchy; embryo straight and small

Nomenclature:

• Urticaceae
  • Jussieu: 400 (1789), under Urticae
  • Endlicher: 282 (1837)
  • Weddell: 1 (1856)
  • Weddell: 401 (1857)
  • Weddell: 32 (1869)
  • Bentham: 341 (1880)
  • Engler: 98 (1888)
  • Roessler: 1 (1967)
  • Friis: 79 (1991)
  • Friis: 612 (1993)

Distribution & Notes:

• Global: Genera ± 50, species ± 1 000, widely distributed in the tropical and, with fewer species, in temperate regions
• Southern Africa: Genera 11, species 22

References:

• BENTHAM, G. 1880. Tribus Urticeae. In G. Bentham & J.D. Hooker, Genera plantarum 3. Lovell Reeve & Co., London
• ENDLICHER, S.L. 1837. Urticaceae. Genera plantarum secundum ordines naturales disposita. Beck, Vienna
• ENGLER, A. 1888. Urticaceae. Die natürlichen Pflanzenfamilien 3,1
• FRIIS, I. 1991. Urticaceae. Flora zambesiaca 9,6
• FRIIS, I. 1993. Urticaceae. In K. Kubitzki, J.G. Rohwer & V. Bittrich, The families and genera of vascular plants - dicotyledons 2. Springer-Verlag, Berlin
• JUSSIEU, A.L. DE. 1789. Urticae. Genera plantarum secundum ordines naturales disposita. Herissant & Barrois, Paris
• MABBERLEY, D.J. 1997. The plant-book, edn 2. Cambridge University Press, Cambridge
• ROESSLER, H. 1967. Urticaceae. Prodromus einer Flora von Südwestafrika 17
• WEDDELL, H.A. 1856. Monographie de la famille des Urticacées. Gide & J. Baudry, Paris. Reprinted in Archives du Muséum d'Histoire Naturelle, Paris 9
• WEDDELL, H.A. 1857. Monographie de la famille des Urticacées. Gide & J. Baudry, Paris. Reprinted in Archives du Muséum d'Histoire Naturelle, Paris 9
• WEDDELL, H.A. 1869. Urticaceae. In A. de Candolle, Prodromus 16,1. Treuttel & Würtz, Paris.

Resources:

• Classification of Urticaceae
• Key to Urticaceae genera

• Urticaceae genera: