(from Greek hyle, forest), a tropical rain forest in South America, mainly in the Amazon Basin. There are two basic types of gilea: igapo, or várzea, in low-lying areas that are at times flooded by the river and terra firma, in higher, unflooded areas. The terra firma has a large variety of species, especially endemic ones. Characteristic of it are epiphytes (mostly of the family Bromeliaceae, but also including the family Araceae), which are notable for their shapes and the bright colors of the flowers, and cacti (especially Rhipsalis species). Epiphytes form numerous air roots. The gilea has many lianas and some myrmecophilous plants (plants that live symbiotically with ants) of the genera Cecropia and Triplaris. Many valuable species of trees grow in the gilea, for example, cacao and the Para rubber tree; copaiba is obtained there, as well as other useful products.
Gilea type forests also grow in central Africa (mostly in the Congo Basin) and in southwestern Asia.