Urtica dioica Linnaeus (1753: 984) subsp. dioica

Weigend, Maximilian & Luebert, Federico, 2009, Weeding the nettles I: Clarifying species limits in perennial, rhizomatous Urtica (Urticaceae) from southern and central Chile and Argentina., Phytotaxa 2, pp. 1-12 : 7

1. Urtica dioica Linnaeus (1753: 984) subsp. dioica .

Lectotype (designated by Woodland, 1982: 283): anon., Herb. Linnaeus 1111.8 (LINN!, photographs: AUB, DAO, MTMG). — Fig. 1 A .

Urtica dioica subsp. dioica is a widespread nitrophilous weed, common throughout Europe, western Asia, northern Africa and eastern North America. It is also found on several islands in the North Atlantic (e.g., Iceland). The typical subspecies is here reported for the first time from South America, probably from introduced populations. It can be readily differentiated from the native species by its very dense pubescence of stinging hairs on the abaxial leaf veins, its usually much wider and more triangular leaves (in the weedy form found in South America) and its predominantly dioecious populations. Numerous monoecious individuals of U. dioica subsp. dioica have been reported, but these always make up only individual clones in a population, with the bulk of individuals unisexual (Heemskerk et al. 1998). So far, monoecious individuals have not been reported from South America. Urtica dioica subsp. dioica is likely much more common in southern South America than is reflected by the number of specimens studied, as botanists may refrain from collecting it, recognizing it as an introduced weed. It is likely to be locally common in pastures and on road sides in southern and central Chile and Argentina.

Representative specimens: ARGENTINA: Prov. Córdoba, Depto. Río Segundo, Río Segundo , en “Las Compuertas”, 13.11.1970, R. Subilis 1084 (sterile, MO) . CHILE: VIII Región, Bío-Bío: Prov. Concepción, Río Bío-Bío estuary, 30 m, 36º49' S, 73º10' W, 23.08.1968, C. W. O´Brien s.n. (male, CONC) . IX Región, Araucanía: Prov. Cautín, Villarica , 220 m, Jan 1962, G. Montero O. 6531 (female, CONC) . XIV Región, de Los Ríos: Prov. Valdivia, Valdivia , Isla Teja , 70 m, Dec. 1961, H. Gunckel 38.813 (female, CONC) .

Figures

FIGURE 1. Flower, fruit and indument of Urtica: A, mature achene of U. dioica subsp. dioica (Henning & Schneider 313, B). B, mature achene of U. magellanica (Weigend 6078-C). C, nearly mature achene of U. mollis (Ricardi et al. 720). D, same, as enclosed in densely pubescent perianth (Ricardi et al. 720). E, sparsely pubescent adaxial leaf lamina of U. magellanica (Gunckel 46.420). F, sparsely pubescent adaxial leaf surface of U. magellanica (Riquelme 18). G, sparsely long-pubescent abaxial leaf surface of U. magellanica (Riquelme 18). H, densely pubescent adaxial leaf surface of U. mollis (Villagrán 1827). I, densely pubescent abaxial leaf surface of U. mollis (Villagrán 1827).