Glabrous or finely pubescent perennial. Stems numerous, ascending, flexuous or decumbent, rarely erect, 10-25 cm, leafy, branched in upper part. Leaves thick, almost glabrous, rarely finely pubescent. Basal and lower cauline leaves ovate, to 4-6 cm, petiolate; median largest, ovate to broadly ovate with sometimes cordate base, 1-7 x 0·7-4 cm, acutely dentate, bidentate or irregularly dentate, obtuse or acute, petiolate; uppermost oblong-lanceolate, ± sessile. Flowers 1-4, erect, pedicellate, in almost corymb-like inflorescence. Calyx lobes very variable in size and form, broadly triangular to lanceolate, acute, 6-15 x 4-6 mm, subentire, glabrous or pubescent, spreading-erect, patent after flowering. Calyx appendages lanceolate, acute, 2-5 mm or absent, shorter than obconical ovary. Corolla campanulate, 16-35 x 10-30 mm, divided to ¼ into ovate, acute lobes, white or pale pink, glabrous or slightly pubescent outside. Style included. Stigmas 3. Capsule erect, obconical 6-4 mm. Seeds ellipsoid, 1 x 0·4 mm, dark brown, shiny. FI. 5-9. Crevices of volcanic igneous and limestone cliffs, 250-2285 m.
Endemic. Euxine element.