A Genus with about 100 species, most are native from the Mediterranean area and islands in the Atlantic Ocean, were they are found growing on cliff tops, plains and under forest cover.
They grow under hot dry conditions for most of the year. Under glass they should be grown in a soil-based medium in full sun. Water when dry but in the winter water very infrequently. In warm zones grow along foundations or in a rock garden or on walls and use a dry winter mulch in the fall. The pH should be neutral to slightly alkaline and soils moderately rich in nutrients.