Stout to very slender, 4-15 dm; lf-blades deltoid, the larger 1-2 dm, on elongate petioles, mostly 2-3 times compound, the upper once or twice compound, on short, broadly winged petioles; lfls lanceolate to ovate, 1.5-4 cm, pinnatifid; umbels few, 3-12 cm wide, long-peduncled; rays and pedicels many; fr elliptic or oblong, 2.5-4.5 mm; 2n=44. Swamps, bogs, and wet meadows; Lab. and Nf. to Minn., s. to Pa., Ind., and Io., and in the mts. to N.C. Aug., Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Very rare. Two of my specimens were collected in dense shade on the south banks of streams in springy places in sandy-gravelly soil made miry by large springs, and I found it in a tamarack bog in La Porte County. Grimes collected a specimen in damp soil on a rocky slope along Sugar Creek in Montgomery County. It has also been reported from Carroll and Noble Counties and from the area of Delaware, Jay, Randolph, and Wayne Counties.
Indiana Coefficient of Conservatism: C = 10
Wetland Indicator Status: OBL
Diagnostic Traits: glabrous perennial; leaves finely 2-3× compound; leaflets pinnatifid; umbels subtended by short, linear-filiforms bracts; petals white; fruits flattened, ellipsoidal, winged and prominently ribbed, ca. 4.5-6 mm long.