This genus of plants includes shrubs, sub-shrubs and some herbaceous perennials. Many are grown for their foliage as well as their flowers, which are found in blue, white, pink and yellow. The foliage is often silver and can be aromatic.
There are around 100 species, mainly from the Mediterranean, but also growing in Asia, Australia and New Zealand, in dry scrubland.
They prefer full sun and well-drained soil. Some varieties can be tender, and all are best planted in a sheltered spot.