Abstract: 1. In the present paper 27 species and 4 varieties of the genus Petrocosmea are recognized and classified into three sections defined largely by relative lengths of the upper and lower corolla lips and external morphology of the anther. Of the three groups sect. Petrocosmea is considered the primitive one, while the other two may be both derived from it. The species of each section are mostly closely interrelated and distinguished from each other often by tiny characters. 2. According to the morphological investigations on the genus in question some essential evolutionary trends of it are revealed as follows.

Key words: Gesneriaceae