Two classes of ant-epiphyte relationships have drawn the attention of naturalists: epiphytes that provide chambers within which ants nest (domatia), and ants that plant epiphyte seeds in carton nests, producing "ant gardens." Ants are major movers and formers of organic matter in the canopies of lowland tropical forests, and ant derived accumulations of organic matter provide substrate for the establishment of many vascular epiphytes. This very general relationship may lead to some epiphyte species becoming specialized ant associates, either as components of ant gardens or as epiphytes providing domatia. In only one case is there evidence that coevolution has occurred. Epiphytes appear to have evolved specific adaptations for life with ants, but rarely have ants been shown to have specific adaptations to epiphytes.