Vines, perennial; roots thin, fibrous. Stems scandent, tendril-bearing, glabrous or pubescent; tendrils terminating branches, simple to branched. Leaves cauline, alternate, petiolate; ocrea persistent, chartaceous; blade ovate to ovate-lanceolate, margins entire. Inflorescences terminal and axillary, paniclelike, usually pedunculate. Pedicels 3-winged, 1 wing more prominent and becoming greatly expanded in fruit, glabrous. Flowers bisexual, (1-)3-5 per ocreate fascicle, base stipelike; perianth accrescent, greenish to greenish yellow, campanulate, indurate, glabrous; tepals 5, connate proximally, petaloid, slightly dimorphic, subequal; stamens 8; filaments distinct, adnate proximally to perianth tube, glabrous; anthers pink to red, oval; styles 3, erect or spreading, distinct; stigmas 3, depressed-capitate. Achenes included in indurate perianth, tan to brown, unwinged, obscurely 3-gonous proximally, 3-gonous distally, glabrous. Seeds: embryo straight. x = 24.

Fls perfect; tep 5, connate at base; stamens 8; styles 3, with 2- lobed stigma; fr an achene enclosed by the accrescent, coriaceous perianth; base of perianth and its pedicel above the joint winged on one side, the whole resembling a samara; vines, climbing by tendrils terminating short, few-lvd lateral branches, with alternate, petiolate lvs; fls in small fascicles spicate on a long axis; ocreae none; stipules represented by a narrow pubescent ring around the stem. Monospecific.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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