D. sylvestris: biennial; stems erect, 4-5 feet high, prickly as well as the midribs, peduncles, and involucres; leaves sessile, long, lanceolate, entire or coarsely-toothed, the upper ones broadly-connate at the base; heads of flowers at first ovoid, but gradually becoming cylindrical, nearly three inches long, the involucre of 8-12 long, unequal, stiff, linear, prickly bracts, usually curved upwards; flowers pale lilac. - Roadsides and waste places. Fl. July.
The Fullers' Teasel (D. fullonum) is believed to be a cultivated variety, differing only in the scales of the receptacle being hooked.
D. pilosus: biennial; stems 2-4 feet high, branching, with stiff spreading hairs or bristles; leaves with a large ovate coarsely-toothed terminal segment, and 1-2 pairs of smaller ones; flowers white, forming globular, hispid heads, barely an inch in diameter, on long peduncles. - Moist hedges, thickets, and banks. Fl. August.