Peponopsis Naudin, Ann. Sci. Nat., Bot., ser. 4, 12: 88. 1859.
Type: Peponopsis adhaerens Naudin, C.V. Naudin s.n. (P (holotype), F, K (isotypes)), cultivated at Paris Botanical Gardens from seeds sent from Northeastern Mexico.
Perennial climber with more or less woody, up to 8-10 m long shoots and dioecious sex system. The leaves are simple, petiolate, with broadly ovate-cordate, unlobed to 3-5-lobed blade, 10-18 cm long, usually with a few disc glands near the leaf base. The tendrils are multifid, densely short-villous, with apical adhesive pads. The flowers are medium-sized, solitary, axillary. The receptacle-tube is obconic-tubular, apically expanded. The five sepals are ovate-lanceolate in male flowers and up to 2 cm long, in female flowers the sepals are triangular-lanceolate, acute, 6-7 mm long. The corolla is white to greenish-white, broadly campanulate with five, halfway-fused, broadly obovate-oblong, rounded petals, up to 4 cm long. The three stamens are inserted near the base of the tube on free, 5 mm long filaments. Two anthers are bithecous, one is monothecous. The thecae are much convoluted and contain echinate pollen. The ovary is ovoid, glabrous with three placentae and many, horizontal ovules. The style is 12-14 mm long, with three papillose, oblong to ovate-oblong stigmata. The fruit is a fleshy, subglobose pepo, 8-10 cm across. At maturity, the fruit splits into three carpellar segments and exposes c. 200, ovate-oblong seeds, 4-9 by 2-5 mm, compressed. The testa is greenish to grey, finely perforate, with narrowly winged margin.
The only species is extremely rare in pine forest in Mexico (Querétaro, Hidalgo, Puebla and Veracruz) where it grows from between 800-1500 m a.s.l.
Peponopsis is the sister lineage to the genus Cucurbita in tribe Cucurbiteae, from which it split about 16 million years ago (Schaefer et al. 2009).
Peponopsis adhaerens Naudin, Ann. Sci. Nat., Bot., ser. 4, 12: 89. 1859.
Jeffrey, C. 1971. Further notes on Cucurbitaceae: II. Kew Bull. 25: 191-236.
Schaefer, H. and S.S. Renner. 2011. Phylogenetic relationships in the order Cucurbitales and a new classification of the gourd family (Cucurbitaceae). Taxon 60: 122-138.