3. Urtica urens L. (dwarf nettle, burning nettle)

Pl. 571 h; Map 2676

Plants annual, with taproots. Stems 15–50(–80) cm long, erect or ascending, unbranched or branched from the base, moderately to densely pubescent with stinging hairs, otherwise moderately pubescent with short, nonstinging hairs. Stipules 1–4 mm long, oblong to narrowly oblong or linear. Leaf blades 2–9 cm long, more or less the same size along the stem (the upper leaves only slightly smaller than the others at maturity), elliptic to broadly elliptic or occasionally ovate, narrowly to broadly angled or occasionally rounded at the base, the margins mostly sharply and relatively coarsely toothed (sometimes appearing doubly toothed, the main teeth having smaller teeth along their margins), the surfaces sparsely to moderately short-hairy, the undersurface or both surfaces also with scattered stinging hairs along the main veins, sometimes lighter green but not purplish-tinged; cystoliths rounded. Inflorescences mostly shorter than the subtending petioles, small, globose clusters, these more commonly appearing as short, dense, spikelike racemes, rarely appearing as small panicles, the staminate and pistillate flowers mixed in the same inflorescence. Pistillate flowers with the 2 smaller sepals 0.5–0.7 mm long, ovate, the 2 larger sepals 0.6–0.9 mm long, broadly ovate. Fruits 1.5–1.8 mm long. 2n=24, 26. May–September.

Introduced, (native of Europe, Asia; introduced widely, in temperate North America most abundantly in the western U.S., sporadically farther east and in Canada). Bottomland forests; also moist disturbed areas.

Steyermark (1963) mentioned an additional occurrence of this species in Clark County, but this could not be verified during the present study.