Urtica dioica L. ssp. dioica, Sp. Pl. 984. 1753.
Hierbas anuales ca. 0.4 m de alto, tallos con two types of tricomas, tricomas presumed to be urticantes, bulbous based/stalked, clear above stalk, straight and spreading to curving upward, ca. 1—1.5 mm and smaller trichomes curving and opaque; plantas dioecious. Hojas opposite, those at a node similar in size and shape, lanceolate, 2.5—4.2 cm de largo y 1.2--2 cm de ancho, ápice long- acuminado, base nearly truncada, sub-cordate, margen gruesamente dentado con 3--6 dientes/cm, cistolitos punctiform, visibles sólo en la haz, tricomas urticantes and non-urticating dispersos en la superficie de la haz y sobre los nervios en el envés, nervadura strongly palmately 3-nerved from base, sometimes with an additional basal pair of veins, with 2 or 3 additional pairs of lateral veins; estípulas free, connivent interpetiolarly. Inflorescencias two per node, spiciform but branching at base, 1.5—2.5 cm, flowers in sessile close set glomerules, with tricomas urticating and non-urticating numerous; flores masculinas not seen; flores femeninas con perianto 4-partido, the larger 2 enclosing the ovary, ca 0.75 mm, ovados, estigma sessile and penicillate. Aquenio not seen.
Known in Nicaragua from one collection (Rueda 18139, HULE), weed at finca, Estelí, 850 m, fl jun, fr not seen; native to Old World, now cosmopolitan in temperate regions. The genus is found world wide and has an estimated 30 species. The above description based on sole Nicaraguan collection seen. Staminate inflorescences are similar to the pistillate; the staminate perianth is also 4-parted and ca. 1—1.25 mm wide. Urtica dioica differs from U. leptophylla Kunth (Guatemala, Costa Rica to Bolivia and Venezuela) most markedly in its free stipules vs. in U. leptophylla stipules interpetiolarly connate for at least half their length.
D. W. Woodland. Biosystematics of the perennial North American taxa of Urtica. II. Taxonomy. Syst. Bot. 7: 282--290. 1982.