Glaucium flavum Crantz
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Stout biennial or perennial 3–9 dm; lvs firm, hairy, the lowest petioled, the others sessile or nearly so, ovate or oblong, irregularly pinnatifid; fls 5–9 cm wide, their short peduncles strongly thickened at maturity; fr 15–30 cm, 5 mm thick; 2n=12, 24. Native of Europe, established in waste places, especially near the coast, from Mass. to Va., and occasionally inland to Mich. June. (G. glaucium)