3. Aristolochia macrophylla Lamarck, Encycl. 1: 255. 1783.
Aristolochia sipho L'Héritier
Lianas , twining, to 20 m, woody. Young stem ribbed, glabrous. Leaves: petiole 4-6 cm. Leaf blade reniform, 7-34 × 10-35 cm, base cordate, sinus depth 1-4.5 cm, apex obtuse to acute or acuminate; surfaces abaxially glabrous to slightly puberulent; venation palmate-pinnate. Inflorescences on new growth, axillary, solitary flowers; peduncle bracteolate, 3-7 cm; bracteoles reniform, to 15 mm. Flowers: calyx yellow-brown marked with red-brown, strongly curved; utricle pendent, globose to cylindric, 0.5-1.5 × 0.8-1 cm; syrinx absent; tube curved or bent and angled upward, cylindric, 1-3 × 0.3-0.5 cm; annulus smooth; limb yellow to brown, 3-lobed, lobes 1.5-2 × 1.5-2 cm, glabrous; gynostemium 3-lobed, globose to crown-shaped, 4 mm; anthers 6; ovary 3-locular, 3-7 cm. Capsule ovoid to cylindric, 6-8 × 4-10 cm, dehiscence basipetal; valves 6; septa entire, not attached to valves. Seeds * flat, triangular, 1 × 1 cm. 2 n = 28.
Flowering late spring-summer. Forests, often on dissected uplands and rugged, rocky slopes; Cumberland and Blue Ridge mountains; 50-1300 m; Ont.; Ga., Ky., Md., N.C., Pa., S.C., Tenn., Va., W.Va.
Aristolochia macrophylla has possibly escaped from cultivation in Connecticut, Maryland, Massachusetts, New Jersey, New York, and Vermont; these are not documented.
The name Aristolochia durior Hill has been misapplied to this species.
The Cherokee applied decoctions made from the roots of Aristolochia macrophylla directly to feet and legs to alleviate swelling; they ingested a compound infusion of "stalk chips" for yellowish urine (D. E. Moerman 1986).
The leaves of Aristolochia macrophylla are eaten by larvae of the eastern pipe-vine swallowtail butterfly, Battus philenor philenor (Linnaeus) (W. H. Howe 1975).