A genus of annual and perennial herbs whose opposite, entire leaves without stipules are usually sessile. The plants are glabrous. The flowers are regular and bisexual. The calyx is lobed, the corolla a cylindrical tube, usually white, blue, or purple, composed of 4 or 5 petals. There are 4 or 5 stamens. The ovary is superior and unilocular with numerous ovules. The style is sometimes absent. The fruit is a capsule containing many small seeds. There are about 125 species, found in all temper-ate regions except Africa. Most species occur on mountain grassland, calcareous pastures, and in coastal habitats.
Subjects: Plant Sciences and Forestry.