Glabrous perennial 2-7 dm; stems 1-several from the base, simple below the infl; lvs mostly 10-40 below the infl, elliptic to oblanceolate or obovate, 1.5-2.5 cm נ3-6 mm, the lower opposite, the upper often alternate; stem with a single narrow wing decurrent from the base of each lf but not extending to the lf below; infl open-corymbiform, typically with a few rather long, slender, ascending-spreading branches; pedicels 2-8(-10) mm, terete or nearly so; sep lance- ovate, the outer acute, entire, 2-4 mm, the inner shorter, broader, often with a few tiny sessile glands along the margins; pet yellow, 3.5-5.5 mm; fr depressed-globose, scarcely 2 mm, readily splitting into 10 mericarps, shattering and falling; false septa nearly complete, glabrous; true septa usually sparsely ciliate; 2n=36. Upland woods; Mass. and s. Ont. to s. Mich., n. Ill., and Mo., s. to Ga. and Ala., southward mostly avoiding the coastal plain. June, July. (Cathartolinum v.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.