Helmontia Cogn., Bull. Soc. Roy. Bot. Belgique 14: 239. 1875.
Type: Helmontia leptantha (Schltdl.) Cogn.; basionym: Anguria leptantha Schltdl., H. Kegel s.n. (HAL?), Suriname, Geyersvliet, 1845.
Perennial climber with several meters long herbaceous or woody shoots and monoecious sex system (often appearing dioecious). The leaves are simple, petiolate, with unlobed or palmately lobed or trifoliolate blade. The tendrils are simple. The flowers are small, male flowers many (>100 per inflorescence), produced in racemes or umbels, the female flowers are produced in pendulous racemes. The receptacle-tube is obconic to cylindrical with five small, triangular, reflexed sepals. The five petals are yellowish-green, free, c. 3 mm long. The two stamens are inserted near the mouth of the tube on free filaments. The anthers are bithecous. The thecae are straight and contain triporate, perforate or reticulate, medium-sized pollen (polar axis 51-69 µm, equatorial axis 62-74 µm, (Khunwasi 1998)). The fruits are fleshy, ovoid to ellipsoid, indehiscent, ripening yellowish-green. The many seeds are smooth, oblong-elliptic, compressed.
Three species growing in tropical forest of Guyana, Venezuela, and Brazil.
Phylogenetically, Helmontia groups with Gurania and Psiguria in tribe Coniandreae (Schaefer et al. 2009; Schaefer & Renner 2011).
Helmontia cardiophylla Harms, Notizbl. Bot. Gart. Berlin-Dahlem 11: 772. 1933.
Helmontia leptantha (Schltdl.) Cogn., Diagn. Cucurb. Nouv. 1: 20. 1876.
Helmontia trujilloi C. Jeffrey, Kew Bull. 33: 352. 1978.
Jeffrey, C. and B. Trujillo. 1992. Cucurbitaceae. In G. Morillo (ed.). Flora de Venezuela 5, 1: 11-201. Caracas.
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.