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.