Dipsacus fullonum ssp. sylvestris

General:
Biennial herb from a taproot; stems erect, stout, angled, few-branched, increasingly prickly upwards, 0.5-2.0 m tall.

Leaves:
Basal leaves oblanceolate, toothed, in rosettes; stem leaves lanceolate, opposite, simple, more or less prickly, especially on the midrib, otherwise glabrous, the pairs usually only shallowly fused around the stem, toothed below, becoming entire upwards, up to 50 cm long.

Flowers:
Inflorescence of 3-10, egg-shaped to nearly cylindrical heads, terminating long naked stalks, the heads persisting through winter; corollas lavender, rarely white, funnel-shaped, shallowly 4-lobed, hairy, 10-15 mm long; calyces cuplike, 1 mm long, 4-angled or 4-lobed, silky; involucral bracts unequal, more or less prickly, linear, stiff, curved upwards, the longer ones surpassing the heads; receptacles scaly, these ending in spines.

Fruits:
Achenes, 5-8 mm long, 4-angled, hairy.

Source:  The Illustrated Flora of British Columbia