Stinging nettle in British Columbia is represented by two subspecies: 1) Urtica dioica spp. dioica (which is an introduced taxon in North America) and Urtica dioica ssp gracilis (which is the native stinging nettle). Urtica dioica ssp gracilis is found throughout most of North America, while subspecies dioica is found mainly in the eastern and western states and provinces (AK, AL, CA, CT, DC, DE, FL, GA, IL, IN, MA, MD, ME, MI, NC, NH, NJ, NY, OH, OK, OR, PA, RI, SC, TN, VA, VT, WA, WV and BC, NB, NF, NS, ON, PE, QC), but is absent from the mid-west and prairie provinces (USDA 2010). In BC, the native subspecies is widespread, while the distribution of the introduced subspecies is not fully known. There are confirmed observations from the Greater Vancouver area (Vancouver, Burnaby, New Westminster, Surrey, Coquitlam), it is to be expected on Vancouver Island, and it may be present in the BC interior (Frank Lomer pers. com. 2010). It is confirmed on Valdes Island (see photo #24310). Further work is needed to clarify its extent of occurrence in the province. The two subspecies are separated by flower morphology, and the presence of stinging hairs on either one or both leaf surfaces. See the identification key below for more details.
Perennial herb from strong rhizomes; stems erect, simple or branched, solitary, smooth except for a few stinging hairs and bristles, 100-300 cm tall.
Basal leaves lacking; stem leaves narrowly lanceolate to widely egg-shaped, opposite, the blades 7-15 cm long, coarsely toothed, stalked; stipules 5-15 mm long.
Inflorescence of male or female flowers in a 1-7 cm axillary panicle on the same or different plants; corollas lacking; sepals 4, 1-2 mm long; female flowers usually uppermost.
Achenes, egg-shaped, flattened, 1.0-1.5 mm long.
The native taxon is best recognized as a single, highly variable subspecies (Bassett et al. 1974, Boufford 1997).
Synonyms and Alternate Names:
Urtica gracilis var. latifolia Farw.
Key to Urtica
1. Plants tap-rooted annuals 10-80 cm tall; inflorescence in dense clusters of mixed male and female flowers; mature achenes triangular................... .....Urtica urens
1. Plants rhizomatous perennials 100-300 cm tall; inflorescence a panicle of either male or female flowers; mature achenes egg-shaped................ .....Urtica dioica
Two subspecies of Urtica dioica are found in BC:
1. Male and female flowers on different plants; leaf blades abaxially hispid, both surfaces with stinging hairs................................ssp. dioica
1. Male and female flowers mostly on the same plants; leaf blades abaxially glabrous or puberulent......................ssp. gracilis
Sources: Illustrated Flora of British Columbia and Flora North America Online.