Annual or perennial herbs, usually monoecious, with scabrid, scandent or prostrate, running, ± succulent stems. Rootstock not tuberous. Tendrils usually branched. Lvs simple, mostly lobed, scabrid or hairy. Fls solitary, usually axillary, large. Calyx 5-lobed. Corolla yellow; lobes 5, extending to c. 1/2 way. Stamens 3; filaments free; anthers united, contorted. ♀ fls similar to ♂ but usually larger and fewer; staminodes 3, rudimentary. Ovary 3-locular, less commonly 5-locular; placentae 3-5; ovules numerous; stigmas 3-(5), 2-lobed. Fr. (pepo) large, variously shaped, indehiscent, consisting of an outer rind and soft ± pulpy interior, with central mass often breaking away from outer wall at maturity and forming a loose fibrous internal ball, with the rind then very hard and shell-like; peduncle persistent, sometimes strongly accrescent. Seeds numerous, flattened, usually white or pale brown, more rarely black; margin often raised.