Climbing sometimes to several m; lvs orbicular in outline, shallowly 3-5-lobed, usually with a deep basal sinus, the lobes denticulate, acuminate; pistillate peduncles eventually 5-8 cm, the staminate usually longer; staminate cor 8-10 mm wide, lobed to the middle; fr ovoid, 1.5 cm, hairy and spiny; 2n=24. Damp soil; Me. and Que. to Minn., s. to Fla. and Ariz. July, Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.