A genus of calcicole herbs, often forming mats, in which the stems are erect, and the leaves are usually oblong, sessile, and numerous up the stem. The flowers are 4-petalled, white, or pale yellow. The fruits are compressed, much elongated, and beakless (see beak). Many species are cultivated for their flowers. There are about 120 species, occurring throughout the northern temperate zone, and in the mountains of Africa.
Subjects: Plant Sciences and Forestry.