Perennial, 60 cm to 2 m tall, stem speckled or evenly purplish (no waxy bloom), solid in center.
Leaves in whorls of 4-5, stalk short; blade 6-20 cm long, 2-9 cm wide, lance-shaped to narrowly elliptic, pointed at both ends, rough on both sides, veins pinnate, margin sharply toothed.
Flowers dull purple, 9-22 per head, bracteate base 0.7-0.9 cm tall, often purplish, bracts overlapping in several rows, blunt-tipped; inflorescence of flat-topped segments, stems often finely sticky-hairy; blooms July-Sept.
Fruit dry, 1-seeded, 5-angled plumed achene. Seeds eaten by some birds (Martin et al. 1951).
Wetland status: FACW.
Frequency in NYC: Occasional.
Habitat: Open moist areas, prefers calcareous soil, probably does well on concrete debris. (USDA, NRCS 2006) lists a range of soil pH 5.5-7.0. Moderately tolerant of shade.