Stylophorum diphyllum (Michx.) Nutt.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Stem 3–5 dm at anthesis; basal lvs several, long-petioled, thin, broadly oblong to ovate, pinnately divided almost or quite to the midvein into 5–7 oblong or obovate, obtusely lobed or toothed segments; cauline lvs 1 pair, smaller than the basal; buds on erect pedicels 2–5 cm; sep hairy; pet 2–3 cm; style 1 cm; fr ellipsoid or thick-fusiform, bristly, 2–3 cm; 2n=20. Rich, moist woods; w. Pa. to s. Mich. and Wis., s. to Tenn. and Ark. Apr.–May.