Linnaea 12: 414. 1838.
Vines perennial. Stems trailing, 50–150 cm, pustulate-scabrous to pustulate-hispid and sparsely hirsute with deflexed hairs; roots fleshy to ± woody, tuberous; tendrils usually unbranched, rarely 2-branched. Leaf-blades elongate-ovate, 1–6 (–11) cm, 3–5 (–7) -lobed, lobes pinnately shallowly lobed or sinuate, margins serrate to dentate, surfaces pustulate-scabrous. Flowers: hypanthium campanulate, 4–8 mm; sepals lanceolate to linearlanceolate, 5 mm; petals obovate-oblong, 6–10 mm. Pepos variegated green and yellow or yellow, green-striped, globose to subglobose, with ± elliptical fissures, 4–7 (–10) cm diam.; rind thin, not durable, mesocarp light yellowish orange to pale-yellow, dry-spongy, intensely bitter. Seeds dark-brown to yellowish orange, ovoid-oblong to ellipsoid, 6 mm. 2n = 22.
Phenology: Flowering Jun–Sep.
Habitat: Peanut fields, pond dikes in cotton fields, fallow fields, waste ground
Elevation: 0–100 m
Introduced; Calif., Mass., Tex., Africa, also in Europe, Asia, Pacific Islands, Australia
Citrullus colocynthis is a traditional food plant in Africa, where it is grown particularly for its edible seeds, which are bitter but nutty-flavored, rich in fat and protein, and eaten whole or used as an oilseed. It has also been a standard cathartic remedy, mostly in combination with other cathartics.
Three main haplotypes within colocynth have been identified via molecular data (F. Dane and P. Lang 2004; Dane and J. Liu 2007; A. Levi and C. E. Thomas 2005).
Colocynth rarely is encountered outside of cultivation. It has been reported as a weed in Texas peanut fields (G. L. Nesom 2011); in Massachusetts, it has been sporadically collected since 1878; in California, it has been collected on a pond dike in an area of cotton fields in Kern County.
"thin" is not a number.