Perennial or rarely annual climbers with up to 30 m long, herbaceous or woody shoots, with or without tuberous rootstock and sometimes with conspicuously swollen base (pachypodium). The sex system is dioecious or rarely monoecious. The lower parts of the stem of N. schefferiana are ornamented with hard, green, 1-2 (-4) cm long thorns. The leaves are simple, lobed or 3-5-foliolate, with subcircular blade. The tendrils are apically bifid. The small flowers are produced in large panicles or racemes. The receptacle-tube is cup-shaped with five free sepals. The corolla is rotate or cup-shaped with five yellowish or greenish petals, which are very short-connate at the base. The five stamens are inserted centrally on free or fused filaments. The anthers are all monothecous with straight thecae, which contain tricolporate, striate, small pollen (polar axis 17-36 µm, equatorial axis 17-35 µm (Khunwasi 1998, van der Ham 1999)). The ovary is cylindrical-clavate, trilocular at the apex and unilocular at the base, with 5(-10) pendent ovules per placenta. The three short styles carry reniform stigmata. The fruit is a cylindrical-clavate capsule, produced solitary or in groups, up to 8 cm long, glabrous or pubescent, apex truncate, opening triradiately. The seeds are compressed, mostly horned or star-shaped with finely tubercled testa or smooth with narrow or broad margin, with membranous translucent wing.
The 14 species grow in humid ravines, deciduous forest, lowland savannah and dry forest, primary evergreen forest, coastal rainforest, and on riverbanks of NE India, Malesia, S China, New Guinea, Australia, and Fiji.
Phylogenetically, Neoalsomitra is sister to Gynostemma from which it split about 39 million years ago (Schaefer et al. 2009). Both are placed in tribe Gomphogyneae (Schaefer & Renner 2011).
Neoalsomitra angustipetala (Craib) Hutch., Ann. Bot. 6: 99. 1942.
Neoalsomitra balansae (Gagnep.) Hutch., Ann. Bot. 6: 101. 1942.
Neoalsomitra capricornica (F. Muell.) Hutch., Ann. Bot. 6: 99. 1942.
Neoalsomitra clavigera (Wall.) Hutch., Ann. Bot. 6: 101. 1942.
Neoalsomitra hederifolia (Decne.) W.J. de Wilde & Duyfjes, Blumea 48: 108. 2003.
Neoalsomitra integrifoliola (Cogn.) Hutch., Ann. Bot. 6: 99. 1942.
Neoalsomitra pilosa W.J. de Wilde & Duyfjes, Blumea 48: 110. 2003.
Neoalsomitra plena (Craib) Hutch., Ann. Bot. 6: 100. 1942.
Neoalsomitra podagrica Steenis, Webbia 11: 192. 1955.
Neoalsomitra sarcophylla (Wall.) Hutch., Ann. Bot. 6: 100. 1942.
Neoalsomitra schefferiana (Cogn.) Hutch., Ann. Bot. 6: 101. 1942.
Neoalsomitra schultzei (Cogn.) Hutch., Ann. Bot. 6: 98. 1942.
Neoalsomitra simplex (Cogn.) Hutch., Ann. Bot. 6: 98. 1942.
Neoalsomitra trifoliolata (F. Muell.) Hutch., Ann. Bot. 6: 100. 1942.
De Wilde, W.J.J.O., Duyfjes, B.E.E. 2003. Revision of Neoalsomitra (Cucurbitaceae). Blumea 48: 99-121.
Hutchinson, J. 1942. Macrozanonia Cogn. and Alsomitra Roem. Annals of Botany 6: 95-102.
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.
Van der Ham, R.W. J. M. 1999. Pollen morphology of Bayabusua (Cucurbitaceae) and its allies. Sandakania 13: 17-22.