Peponium Engl.
Peponium Engl. in Engler & Prantl, Nat. Pflanzenfam. Nachtr. 318. 1897.
Type: Peponium mackenii (Naud.) Engl., replaced synonym Peponia mackenii Naudin 1866, Mac Kenn s.n. (P), South Africa, in Caffraria orientali.
Peponiella Kuntze, Rev. Gen. 3: 131. 1898.

Perennial climbers or trailers with up to 8 m long, herbaceous shoots, some with tuberous rootstock, dioecious. The leaves are simple, petiolate, with ovate-cordate, unlobed or palmately 3-5-lobed blade, and oblanceolate to obovate, up to 18 mm long probract at the base of the petiole. The tendrils are mostly bifid, rarely simple. The flowers are up to 8 cm in diameter, some or all species are sweet-scented and open in the evening (Zimmermann 1922). The male flowers are produced in pedunculate racemes or solitary, often raceme and solitary flower in the same axil, the female flowers are always solitary. The receptacle tube is elongated and cylindrical with five linear-lanceolate sepals. The five white or yellow petals are entire, free, obovate, up to 5 cm long and 4 cm broad. The three stamens are inserted near the mouth of the tube on free filaments. The anthers are all bithecous or two bithecous and one monothecous, fused into a central head. The thecae are triplicate and contain tricolporate, striate, medium-sized to large pollen in continental African species (polar axis 90-98 µm, equatorial axis 92-102 µm (Khunwasi 1998)), in the nine Madagascan endemics tricolporate, reticulate-rugulate, rugulate or striate-rugulate small to medium-sized pollen (polar and equatorial axis 38-82 µm (Keraudren 1968)). The ovary is ellipsoid, hairy, with many, horizontal ovules. The stigma is trilobed. The fruit is fleshy, indehiscent, subglobose to ellipsoid, rostrate, ripening orange or red. The many seeds are elliptic, compressed, with blackish, smooth testa. The chromosome number is n = 12 in P. betsiliense (Keraudren 1968).

The 22 species grow in rainforest, wood-, bush- and grassland, often near open water, in Madagascar, in the Seychelles, in Tropical Africa and in Southern Africa.

Peponium is the sister group to Lagenaria, from which it split about 12 million years ago (Schaefer et al. 2009). Both genera are placed in Benincaseae (Schaefer & Renner 2011).

Literature

Keraudren, M. 1968. Recherches sur les cucurbitacées de Madagascar. Mém. Mus. Hist. Nat. B 16: 122-330.

Khunwasi, C. 1998. Palynology of the Cucurbitaceae. Doctoral Dissertation Naturwiss. Fak., University of Innsbruck.

Page, J.S. and C. Jeffrey. 1975. A palyno-taxonomic study of African Peponium (Cucurbitaceae). Kew Bull. 30: 495-502.

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.

Zimmermann, A. 1922. Die Cucurbitaceen. Beiträge zur Anatomie, Physiologie, Morphologie, Biologie, Pathologie und Systematik. Vols. 1 and 2. Jena: Fischer.