Plants perennial, dioecious, climbing; stems annual, hirsute; roots tuberous; tendrils unbranched or 2-branched. Leaves: blade broadly ovate to suborbiculate, not lobed or angulate, margins serrate to (serrulate) denticulate, surfaces eglandular. Inflorescences: staminate flowers 5-15 in axillary racemes or umbelliform fascicles, less commonly solitary; pistillate flowers solitary (2-3), axillary; bracts absent (present). Flowers: hypanthium shallowly campanulate to subrotate; sepals 5, recurving, linear-lanceolate to narrowly lanceolate; petals 5, distinct nearly to base, yellow, ovate-oblong, 15-25 mm, villous abaxially, papillose-glandular adaxially, corolla campanulate. Staminate flowers: stamens 5; filaments inserted near hypanthium base, distinct; thecae connate, forming central oblong body, sigmoid-flexuous, connective broad; pistillodes present. Pistillate flowers: ovary 3-locular, oblong; ovules 30-70 per locule; style 1, columnar; stigmas 3, 2-lobed; staminodes 5 (4 in approximate pairs), linear. Fruits pepos, orange-red (red or green), oblong-ovoid (ellipsoid), longitudinally furrowed (smooth), densely hispid-hirsute to hirsute or hirsute-villous, irregularly dehiscent. Seeds 100-200, obovoid, flattened, not arillate, margins not differentiated, surface smooth. x = 9.