Actinostemma Griff., Account Bot. Coll. Cantor: 24. 1845.
Type: Actinostemma tenerum Griff., Griffith 2523 (BR, GH, K, M, NY, P, S), India, West Bengal.
Mitrosicyos Maximowicz, Mém. Acad. Imp. Sci. St.-Pétersbourg Divers Savants 9: 112. 1859.
‚Pomasterion Miquel, Ann. Mus. Bot. Lugduno-Batavi 2: 80. 1865.
Bolbostemma Franquet, Bull. Mus. Hist. Nat. Paris II, 2: 325. 1930.
Annual or perennial, herbaceous climbers, with fibrous roots or underground stolons with fleshy, crowded scales at the tip and monoecious or dioecious sex system. The leaves are simple, hastate-cordate, entire or 3-5 lobed, base often with glands, petiolate. The tendrils are apically 2-fid or rarely simple. The flowers are mostly unisexual, rarely bisexual with male flowers in thyrses or racemes (rarely solitary or paired) and female flowers solitary or in fascicles. The receptacle-tube is cup -shaped, the five sepals are linear-lanceolate. The rotate corolla is composed of five ovate-lanceolate or long caudate-acuminate petals. The five (rarely six) stamens are inserted on short, free filaments at the base of the tube and arranged in two pairs and one single free stamen (or rarely three pairs). The anthers are all monothecous with straight thecae and carry small tricolporate, striate pollen (polar axis c. 26-40 µm, equatorial axis c. 21-42 µm, (Khunwasi 1998)). The ovary is subglobose or ovoid, semi-inferior and verrucous with one or three placentae and 2-4 pendent ovules 2-4 and a single short style with two or three reniform stigmata. The fruit is an ovoid, conical, operculate pyxidium with glabrous or echinate surface. The few seeds are ovate and compressed with a rugose testa and denticulate margin. The chromosome number is n = 8 (Probatova and Rudykan 1981).
Three accepted species occur in grassland and thickets near open water. Two of them are found in China and one, A. tenerum, is widespread in Russia, India, China, Taiwan, Korea, Laos, Vietnam, Japan.
Actinostemma biglandulosa Hemsl., Hooker’s Icon. Pl. 27: t. 2622, 2645. 1901.
Actinostemma paniculatum (Maxim.) Cogn., Monogr. Phan. 3: 920. 1881.
Actinostemma tenerum Griff., Pl. Cantor. 25. 1837.
Doronkin, V.M. 1995. Semeistvo Cucurbitaceae v Sibiri. (The family Cucurbitaceae in Siberia.). Bot. Zhurn. 80: 68-71.
Franquet, M.R. 1930. L’ Actinostemma paniculatum Maxim. ex Cogn. doit constituer un genre nouveau de Cucurbitacées. Bull. Mus. Hist. Nat. Paris, II, 2: 324-328.
Khunwasi, C. 1998. Palynology of the Cucurbitaceae. Doctoral Dissertation Naturwiss. Fak., University of Innsbruck.
Probatova, N.S. and E.G. Rudyka. 1981. Chromosome numbers of some vascular plant species from the Soviet Far East. Izvestiya Sibirskogo Otdeleniya Akad. Nauk SSSR, Ser. Biol. Nauk 2 (10): 77-81.
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.