Ibervillea Greene, Erythea 3: 75. 1895.
Type: Ibervillea lindheimeri (A. Gray) Greene; basionym: Sicydium lindheimeri A. Gray, F.J. Lindheimer 612 (MO, GH), United States, Texas, Comal county, Comanche Springs, New Braunfels. 1850.
Maximowiczia Cogn., Monogr. Phan. 3: 726-727. 1881 (nom. illegit.).
Dieterlea E. J. Lott, Brittonia 38: 407. 1986.
Annual or perennial climbers with dioecious sex system, up to 12 m long, herbaceous or woody shoots and large tuberous rootstocks, often partly exposed as fleshy pachypodia. The leaves are simple, petiolate, to 10 cm long and 6 cm broad, unlobed or tri- or pentalobed, often with dissected lobes. The tendrils are simple. Flowers small or less often large, mostly opening during the day, except for in I. fusiformis with strongly fragrant and nocturnal flowers. Male flowers are produced in racemes or fascicles (rarely solitary), the female flowers are always solitary. The receptacle-tube is narrowly campanulate to cylindrical, up to 4.5 cm long, with five small, acute sepals. The corolla is narrowly campanulate with five white or yellowish petals, each 4-25 mm long, entire to bifid, united near the base. The three stamens are inserted near the mouth of the tube on free filaments or the filaments fused into a central column. Two anthers are bithecous, one monothecous with straight thecae containing tricolporate or tetracolporate, reticulate, medium-sized pollen (polar axis 56-68 µm, equatorial axis 56-67 µm, (Khunwasi 1998)). The ovary is ovoid to fusiform or cylindrical with 3-5 placentae and many, horizontal ovules. The style is columnar with 3-5 stigmata. The fruit is a fleshy, indehiscent, globose, ovoid, ellipsoid or fusiform berry, 1.5 to 6 cm in diameter and up to 15 cm long, ripening yellow to red. The many seeds are irregularly ovoid or turgid, scarcely compressed, in orange-red pulp. The testa is smooth or verrucous, transversely ridged or smooth, the margins raised.
Seven species growing in semi-deserts, grassy plains, swampy woodlands, thorn-forest, and on margins of cultivated land, from Texas to Guatemala.
Phylogenetically, Ibervillea is placed in the tribe Coniandreae, where it is sister to Tumamoca (Schaefer et al. 2009).
Ibervillea fusiformis (E.J. Lott) Kearns, Madroño 41: 15. 1994.
Ibervillea hypoleuca (Standl.) C. Jeffrey, Kew Bull. 33: 349. 1978.
Ibervillea lindheimeri (A. Gray) Greene, Erythea 3: 75. 1895.
Ibervillea maxima Lira & Kearns, Sida 14: 223. 1990.
Ibervillea millspaughii (Cogn.) C. Jeffrey, Kew Bull. 33: 348-349. 1978.
Ibervillea sonorae (S. Watson) Greene, Erythea 3: 75. 1895.
Ibervillea tenuisecta (A. Gray) Small, Fl. S.E. U.S. 1136. 1903.
Kearns, D.M. 1994. The genus Ibervillea (Cucurbitaceae): an enumeration of the species and two new combinations. Madroño 41: 13-22.
Khunwasi, C. 1998. Palynology of the Cucurbitaceae. Doctoral Dissertation Naturwiss. Fak., University of Innsbruck.
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.