Urtica dioica

Herbs, perennial, rhizomatous, 5-30 dm. Stems simple or branched, erect or sprawling. Leaf blades elliptic, lanceolate, or narrowly to broadly ovate, 6-20 × 2-13 cm, base rounded to cordate, margins coarsely serrate, sometimes doubly serrate, apex acute or acuminate; cystoliths rounded. Inflorescences paniculate, pedunculate, elongate. Flowers unisexual, staminate and pistillate on same or different plants, staminate ascending, the pistillate lax or recurved. Pistillate flowers: outer tepals linear to narrowly spatulate or lanceolate, 0.8-1.2 mm, inner tepals ovate to broadly ovate, 1.4-1.8 × 1.1-1.3 mm. Achenes ovoid to broadly ovoid, 1-1.3(-1.4) × 0.7-0.9 mm.

Distribution

North America, Mexico, Eurasia.

Discussion

Subspecies 3 (3 in the flora).

Selected References

None.

Lower Taxa

Urtica dioica subsp. dioica, Urtica dioica subsp. gracilis, Urtica dioica subsp. holosericea

Key

1	Plants unisexual, staminate and pistillate flowers on different plants; leaf blades abaxially hispid, both surfaces with stinging hairs.	Urtica dioica subsp. dioica
1	Plants unisexual, staminate and pistillate flowers mostly on same plants; leaf blades abaxially bearing stinging hairs, otherwise glabrous, puberulent, or tomentose and moderately strigose, adaxially without (rarely with a few) stinging hairs.	> 2
2	Stems glabrous or strigose, with a few stinging hairs; leaf blades abaxially glabrous or puberulent.	Urtica dioica subsp. gracilis
2	Stems softly pubescent, also with stinging hairs; leaf blades abaxially tomentose to moderately strigose.	Urtica dioica subsp. holosericea