Lilium philadelphicum L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Bulb 2–3 cm thick; stems erect, 3–8 dm; lvs 5–10 cm, acuminate, at least the uppermost in a whorl of 4–7; fls 1–5, erect; tep red-orange, varying to nearly red or nearly yellow, the blade ovate to lance-ovate, 1–2 times as long as the claw, purple-spotted toward the base, acuminate or bluntly apiculate; 2n=24. June–Aug. Two well marked vars.: Var. philadelphicum, of dry open woods and thickets from N.H. to N.C. and Ky., has the lvs mostly whorled, with or without a few alternate lvs between the whorls, lanceolate to oblanceolate, 10–15(–25) mm wide, the fr 2.5–3.5 cm. Var. andinum (Nutt.) Ker Gawl. (L. umbellatum), in meadows and along shores from O. to Minn., B.C., and N.M. has the lvs mostly alternate, except in the uppermost whorl, narrowly lanceolate to linear, 3–10 mm wide, the fr 4–7 cm.