Urtica urens

Herbs , annual, with taproot, 1-8 dm. Stems simple or branched, erect. Leaf blades elliptic to broadly elliptic, widest near middle, 1.8-9 × 1.2-4.5 cm, base cuneate, margins coarsely serrate, serrations often with lateral lobes, apex acute; cystoliths rounded. Inflorescences spikelike or paniculate. Flowers unisexual, staminate and pistillate in same inflorescence, subsessile to short-pedunculate. Pistillate flowers: outer tepals ovate, 0.5-0.7 mm, inner tepals broadly ovate, 0.6-0.9 × 1.2-1.4 mm. Achenes ovoid, 1.5-1.8 × 1.1-1.3 mm. 2 n = 24, 26.

Flowering spring-summer. Waste places, roadsides, pastures, barnyards, cultivated fields, rich woodlands; 0-700 m; introduced; Greenland; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld., N.S., Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, Ariz., Calif., Conn., Fla., Ill., Iowa, Maine, Mass., Mich., Mo., Nev., N.H., N.Mex., N.Y., Okla., Oreg., Pa., R.I., S.C., Tex., Vt., Wash.; Eurasia.

Within the flora, Urtica urens is most abundant in California and in eastern Canada. The Shuswap used it medicinally for sweatbaths and for pain from rheumatism (D. E. Moerman 1986).

Plant: annual herb; Monoecious, erect, simple or branched, 10-75 cm tall Leaves: elliptic to widely elliptic, the blades 1.8-9 cm long, 1.2-4.5 cm wide; apex acute; base cuneate to widely cuneate; margins coarsely serrate, the serrations often with lateral lobes; cystoliths punctiform INFLORESCENCE: spikelike to paniculate, with both staminate and pistillate flowers, subsessile to short pedunculate Flowers: PISTILLATE FLOWERS with outer tepals ovate, 0.5-0.7 mm long; inner tepals widely ovate, 0.6-0.9 mm long; STAMINATE FLOWERS with 4 equal tepals, 4 stamens, and a rudimentary, cuplike ovary Fruit: FRUITS ovoid, 1.5-1.8 mm long, 1.1-1.3 mm broad Misc: Waste places, roadsides, cultivated fields; to ca. 600 m (2000 ft); spring-summer REFERENCES: Boufford, David E. 1992. Urticaceae. Ariz.-Nev. Acad. Sci. 26(1)2.

Taprooted annual, simple or branched, 2-5 dm, with numerous stinging hairs; lvs long-petioled, elliptic to broadly ovate and blunt or rounded in outline, deeply incised- serrate, the teeth triangular, acute, upper lvs usually larger than the lower; stipules oblong, 1-3 mm, fl-clusters oblong, often shorter than the petioles; achenes triangular, 1.5-2.5 נ1-1.5 mm; 2n=24, 26, 52. Native of Europe, widely distributed elsewhere as a weed, and occasionally found in our range. May-Sept.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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