Inflorescences: involucral bracts with base often truncate to subtruncate, sometimes reniform or cordate; terminal leaflets dark green, margins proximally concave to straight-sided, distally incised, abaxially thinly pubescent. Flowers: sepals (9-)10-21 mm, abaxially thinly pubescent; anthers 0.8-1.2(-1.7) mm. Heads of achenes ±ovoid-cylindric, 8-10(-11) mm diam. 2 n =16.

Flowering spring-summer (May-Jul). Riparian areas, moist cliffs and ledges; 10-1000 m; N.B., Nfld., N.S., Ont., Que.; Conn., Maine, Mass., Mich., Minn., N.H., N.J., N.Y., Vt., Wis.