Description from Flora of China
Herbs, climbing or prostrate, annual. Stem and branches robust. Tendrils 2- to many fid. Leaf blade lobed, base cordate. Plants monoecious; flowers solitary, yellow. Male flowers: calyx tube campanulate, rarely elongate; segments 5, lanceolate or leaflike at apex; corolla campanulate, 5-lobed; stamens 3; filaments free; anthers connected into a head, one 1-celled, two 2-celled; anther cells linear, reflexed; connective not produced; pistillode absent. Female peduncle short; calyx and corolla as in male flowers; staminodes 3, broadly triangular; ovary oblong or globose, with 3-5-placentas; ovules numerous, horizontal; style short; stigmas 3-5-lobed or bifurcate. Fruit large, fleshy, indehiscent. Seeds numerous, compressed, smooth.
About 15 species: warm regions of the Americas, also cultivated in tropical, subtropical, and temperate regions; three species (all introduced) in China.
(Authors: Lu Anmin (路安民 Lu An-ming); Charles Jeffrey)