Canopy-tree to 30 m; lfls 5, dark bluish-green, ±drooping, oblanceolate to narrowly obovate, 10-15 cm, finely serrate, pubescent beneath when young; infls 1-1.5 dm, the pedicels and cal beset with small stipitate glands; cal tubular, 7-16 mm, shallowly lobed; pet 4, dull yellow to sometimes tawny or purplish or reddish, villous on the margin, the lateral ones 1.5-2.5 cm, with broadly elliptic blade and exsert claw, the upper 2-3 cm, with a much smaller blade on a long claw; stamens 7 or 8, equaling or shorter than the pet; fr smooth, 5-8 cm thick; 2n=40. Rich moist woods; sw. Pa. and s. O. to s. Ill., s. to n. Ga. and n. Ala. May, June. (A. octandra) Hybridizes with no. 2.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.