Alsomitra (Blume) Spach
Alsomitra (Blume) Spach, Hist. Nat. Vég. Phan. 6: 187. 1838.
Type: Alsomitra macrocarpa (Blume) M.Roem., C.L. Blume 1353 (L), Indonesia, Java.
Macrozanonia Cogn., Bull. Herb. Boissier 1: 612. 1893.
Perennial liana with dioecious sex system, growing to 30-50 m long up into the canopy of tall tropical trees. The woody stem can reach up to 15 cm in diameter. The leaves are to 16 cm long, simple, broadly ovate to rounded-ovate, the margin is entire or rarely trilobed, the petiole with a basal ring-shaped callus. Young plants have a very different, c. 1 cm long distichous leaves, with an oblong, hastate, more or less auriculate blade. The tendrils are apically bifid, with elongated adhesive pads. The small flowers of both sexes are arranged in panicles or racemes. The flowers are campanulate with a fused calyx, which at anthesis tears into (2-)3(-4) irregular parts. The five petals are narrowly elliptic, acute, and papillose at the apex. The three stamens are inserted on short filaments near the mouth of the tube, either with three bithecous anthers or two bithecous and one monothecous anther. The thecae are straight, vertical, and papillose hairy with small pollen grains (polar axis 19-26 µm, equatorial axis c. 21 µm), tricolporate, perforate to indistinctly rugulate (Khunwasi 1998, van der Ham 1999). The ellipsoid ovary comprises three apical placentae, each with many pendent ovules. The three styles carry fleshy bilobed stigmas. The fruit is a large, ovoid-globose to ovoid-cylindrical capsule, 20-25 cm in diameter, which opens high in the trees into three valves and releases the many seeds. Each of the seeds consists of a compressed, suborbicular to elliptic, 25-30 by 20-23 mm sized grain with large, membranous, butterfly-like wings, 10-12 cm wide. The cotyledons remain in the seed during germination.
The only known species, A. macrocarpa (Blume) M. Roem., occurs in tropical lowland riverine forests on rich clay soil in Thailand, Malaysia, Indonesia, the Philippines, and New Guinea. The flowering time is December to January; the fruits ripen March to June.
Alsomitra is placed as sister lineage to all remaining Cucurbitaceae in current phylogeny estimates (Schaefer & Renner 2011).
Alsomitra macrocarpa (Blume) M.Roem., Hist. Nat. Vég. Phan. 6: 187. 1838.
Duyfjes, B. E. E. and W. J. J. O. de Wilde. 1998. Revision of Alsomitra Spach. In: Proceedings of the 4th International Flora Malesiana Symposium 1998. Forest Research Institute Malaysia, Kuala Lumpur, pp. 101-105.
Hutchinson, J. 1942. Macrozanonia Cogn. and Alsomitra Roem. Annals of Botany, N. S. 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.
van der Ham, R.W.J.M. 1999. Pollen morphology of Bayabusua (Cucurbitaceae) and its allies. Sandakania 13: 17-22.