Zanonia L., Syst. Nat., ed. 10. 2: 1292. 1759.
Type: Rheede, Hort. Malab. 8: t. 49. 1688. (Lectotype designated by Aubréville & Leroy, Fl. Cambodge Laos Viêt-Nam 15: 18. 1975. (t. 47-49), specific plate (t. 49) designated by Chakravarty in Thothathri (ed.), Fasc. Fl. India 11: 126. 1982.
Up to 15 m long woody liana with dioecious sex system. The leaves are simple, shortly petiolate, ovate-oblong, and coriaceous. The tendrils are apically 2-fid, rarely simple, in juvenile plants with apical adhesive pads up to 5 mm in length. The flowers are tiny with saucer-shaped receptacle tubes. The male flowers are produced in pendent, many-flowered and up to 60 cm long panicles, the female flowers in up to 40 cm long racemes. The 3-4 sepals 3-4 are c. 2 mm long. The 5 petals are free, fleshy, 2.5-7 mm long and cream-coloured. The 5 stamens are inserted centrally on short, thick, free filaments. The monothecous anthers carry horizontal thecae with small, 3-colporate, striate pollen (polar axis c. 40 µm, equatorial axis c. 29 µm) (Khunwasi 1998). The ovary is clavate, 3-locular at the apex and 1-locular at base with 3 placentae and 2 pendent ovules per locule. The 3 short styles carry bifid stigmas. The staminodes are very small or absent. The fruit is a pendent dry capsule reaching 10 x 5 cm. It is elongate-cylindrical and claviform in shape with truncate apex, dehiscent by a 3-radiate, apical slit into 3 valves. The few seeds are ovate, compressed with a smooth testa and large leathery wing reaching up to to 8 x 2 cm.
The only species, Z. indica L., is distributed throughout tropical Asia from India and Bhutan in the West to Southern China, Philippines, Indonesia, and New Guinea. It is never common and prefers forest edges, gallery forests, and open forest on mountain slopes reaching altitudes of up to 2300 m asl.
Zanonia is the sister lineage to the morphologically similar South American genus Siolmatra. The split between the two lineages is estimated to 20-30 million years ago (Schaefer et al., 2009).
Zanonia indica L., Syst. Nat. (ed. 10.2). 1292.1759.
Khunwasi, C. 1998. Palynology of the Cucurbitaceae. Doctoral Dissertation Naturwiss. Fak., University of Innsbruck.
Schaefer, H., Heibl, C., Renner, S.S. 2009. Gourds afloat: a dated phylogeny reveals an Asian origin of the gourd family (Cucurbitaceae) and numerous oversea dispersal events. Proc. R. Soc. B 276: 843–851.