Abstract. This article reflects the theoretical analysis of the systematical, morphological and ecological aspects of the following green ranides: Rana ridibunda Pallas, 1771, Rana lessonae Camerano, 1882 şi Rana kl. esculenta Linnaeus 1785 (Amphibia: Ranidae). The listed species form the green ranides complex (Rana kl.esculenta complex); which is composed of parental species Rana lessonae Cam. and Rada ribiduna Pal. and the species derived from the process of hybridization of these species – Ranakl. esculenta L. The reason of hybridization phenomenon expression is determined by the lack of genetic isolation of the first generation individuals, this being derived from the natural crossing of the first two species (R. ridibunda, R. lessonae) and the high sexual activity of the R. lessonae males, during the breeding period. R. esculenta hybrid does not show any result of parental species interbreeding but its existence is assured as well by its subsequent hybridization with one of the parental species. Also, the article elaborates on mechanisms of elaboration and operation of the green ranides’ adaptation system – capable of ensuring the existence of its population within fluctuating ambient conditions.