Hog Peanut (Amphicarpaea bracteata)
A vine that twines its way through the underbrush along creeks and streams, dangling clusters of flowers in white, pink, or purple. These flowers produce seeds, but the vine also grows less showy flowers near the ground that turn into a single underground seed, like a peanut. This vine was found in Bird Park in Mount Lebanon.
Gray describes the genus (listed as Amphicarpa) and species (listed as A. monoica):
AMPHICARPA Ell. HOG PEANUT
Flowers of 2 (or 3) kinds; those of the racemes from the upper branches perfect; those near the base and on filiform creeping branches with the corolla none or rudimentary, and few free stamens, but fruitful; reduced flowers of slightly different form sometimes also on aerial racemes. Calyx about equally 4 (rarely 5)-toothed. Stamens diadelphous. Pods of the upper flowers, when formed, somewhat scimiter-shaped, stipitate, 3-4-seeded; of the lower ones commonly subterranean and fleshy, obovate or pear-shaped, ripening usually but one large seed. Low and slender perennials; the twining stems clothed with brownish hairs. Leaves pinnately 3-foliolate; leaflets rhombic-ovate, stipellate. Petals purplish. Bracts persistent, round, partly clasping, striate. as well as the stipules. (Name from amphi, both, and karpos, fruit, in allusion to the two kinds of pods.) FALCATA Gmel.
A. monoica (L.) Ell. Leaflets thin, 1.3-5 cm. long; racemes nodding; calyx of the upper flowers 4 mm. long; the ovary glabrous except the mostly appressed hairy margin; pod 2.5 cm. long; ovary and pod of the rudimentary flowers hairy. (Falcata comosa Am. auth.; Glycine comosa L. ?) Rich damp woodlands, common. Aug., Sept.