Schizopepon Maxim.
Schizopepon Maxim., Mém. Sav. Étr. Acad. St. Pétersbourg 9: 110. 1859.
Type: Schizopepon bryoniifolius Maxim., Carl J. Maximowicz s.n. (syntypes: GH, M, MEL, S), Russia, Amur.

Annual climbers with herbaceous shoots and dioecious or monoecious sex system (rarely bisexual). The leaves are simple, petiolate, with ovate-cordate or hastate, usually 5-7-lobed blade. The tendrils are bifid. The flowers are small, male flowers usually in racemes, female flowers solitary or few in a raceme. Flowers of hermaphrodite individuals contain three stamens, a short style with three-lobed stigma, and triangular hypogenous ovary. The receptacle-tube is cupular or campanulate with five lanceolate or subulate sepals. The five petals are white, ovate. The three stamens are inserted at the base of the tube on short, free or connate filaments. Two anthers are bithecous, one is monothecous with straight thecae. The pollen is tricolporate, reticulate, small (polar axis c. 43 µm, equatorial axis c. 47 µm, (Khunwasi 1998)). The ovary is ovate or conical, trilocular with one pendent ovule per locule. The short style is crowned by 3(-5), slightly expanded, bilobed stigmata. The fruits are small, ovate or conical, smooth or punctate, 3-valved, apex acute or long-acuminate, indehiscent or valves involute and elastically dehiscing the seeds. The 1-3 seeds are pendent, ovate, compressed with brown, sculptured testa, margin irregularly dentate.

Eight species in river valleys, thickets, forests, on roadsides and mountain slopes up to 3000 m in Russia, India, Myanmar, China, one species in Japan.

Schizopepon is sister to Herpetospermum, from which it split about 29 million years ago (Schaefer et al. 2009, Schaefer & Renner 2011). Together, the two genera form the tribe Schizopeponeae (Schaefer & Renner 2011).

Literature

Lu, A. M. 1985. Studies on the genus Schizopepon Max. (Cucurbitaceae). Acta Phytotaxonomic Sinica 23: 106-120.

Akimoto, J., Fukuhara, T., and K. Kikuzawa. 1999. Sex ratio and genetic variation in a functionally androdioecious species, Schizopepon bryoniaefolius (Cucurbitaceae). American Journal of Botany 86: 880-886.

Fukuhara, T. and J. Akimoto. 1999. Floral morphology and vasculature of Schizopepon bryoniaefolius (Cucurbitaceae). Acta Phytotaxonomica et Geobotanica 50: 59-73.

Khunwasi, C. 1998. Palynology of the Cucurbitaceae. Doctoral Dissertation Naturwiss. Fak., University of Innsbruck.

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.

Schaefer, H., Heibl, C., and S.S. Renner. 2009. Gourds afloat: a dated phylogeny reveals an Asian origin of the gourd family (Cucurbitaceae) and numerous oversea dispersal events. Proceedings of the Royal Society B 276: 843-851.