Herpetospermum Wall. ex Benth. & J. D. Hooker, Gen. 1: 834. 1867.
Type: Herpetospermum caudigerum Wall. ex Chakrav., Indian Journal of Agricultural Sciences 16: 34. 1946 (prev. by Wall. in Numer. List n. 6761. 1832 as nom. nud.), N. Wallich 6761 (K), India, Sylhet; accepted name: Herpetospermum pedunculosum (Ser.) C.B. Clarke.
Edgaria C. B. Clarke, J. Linn. Soc., Bot. 15: 113. 1876.
Warea C. B. Clarke, J. Linn. Soc., Bot. 15: 127. 1876. nom. illegit.
Rampinia C. B. Clarke, J. Linn. Soc., Bot. 15: 129. 1876. nom. illegit.
Biswarea Cogn., Bull. Soc. Roy. Bot. Belgique 21: 16. 1882.
Annual, herbaceous climber with spreading roots and dioecious sex system. The leaves are simple, petiolate, the blade is ovate-cordate, up to 15 cm long, 5-7-lobed or unlobed, with entire or irregularly dentate margin. The tendrils are 2-4-fid. The flowers are medium-sized, showy, fragrant. Male flowers are produced in racemes (rarely solitary), the female flowers are solitary. The receptacle-tube is narrowly tubular below, dilated above and broadly campanulate with five linear to subulate sepals. The corolla is broadly campanulate to rotate with five elliptic, yellow petals, which are fused at the base. The three stamens are inserted in the upper half of the tube on free filaments. Two anthers are bithecous, one is monothecous. The thecae are straight, duplicate or triplicate and contain triporate, baculate, large pollen (polar axis 108-110 µm, equatorial axis 111-134 µm, (Khunwasi 1998)). The ovary is oblong to narrowly ovoid, trilocular with 1-16 ascendent, pendent, or horizontal ovules per locule. The three stigmata are dilated. The fruit is dry, fibrous, broadly oblong to ellipsoid-fusiform, smooth or ribbed, 5-8 cm long, apically dehiscing into 3 valves or opening with an operculum. Each fruit contains 6, 12, 24, or 48, oblong or obovate, compressed seeds with smooth testa and obtuse margin. The chromosome number is n = 11 in H. darjeelingensis (Thakur & Sinha 1973).
Four species growing among shrubs and on riverbanks in India, Myanmar, Nepal, Tibet, and China (Yunnan).
Herpetospermum is placed in the tribe Schizopeponeae and sister to the genus Schizopepon, from which it split about 29 million years ago (Schaefer et al. 2009; Schaefer & Renner 2011).
Herpetospermum darjeelingensis (C. B. Clarke) H. Schaef. & S. S. Renner, Taxon 60: 134. 2011.
Herpetospermum operculatum K. Pradheep, A. Pandey, K.C. Bhatt & E.R. Nayar, Blumea 59: 1. 2014.
Herpetospermum pedunculosum (Ser.) C.B. Clarke, J. Linn. Soc., Bot. 15: 115. 1876.
Herpetospermum tonglense (C.B. Clarke) H. Schaef. & S.S. Renner, Taxon 60: 924. 2011.
Khunwasi, C. 1998. Palynology of the Cucurbitaceae. Doctoral Dissertation Naturwiss. Fak., University of Innsbruck.
McVaugh. R. 1974. Report of the Committee for Spermatophyta: conservation of generic names: 17. Proposal 339 (8606) Herpetospermum C. B. Clarke (1879), vs. Rampinia C. B. Clarke (1876). Taxon 23: 821-822.
Pradheep, K., Pandey, A., Bhatt, K.C. and E.R. Nayar. 2014. Herpetospermum operculatum (Schizopeponeae, Cucurbitaceae), a new species from India, Myanmar, and China. Blumea 59: 1-5.
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.
Thakur, G.K., Sinha, B.M.B. 1973. Cytological investigation in some cucurbits. J. Cytol. Gen. 7/8: 122-130.