This genus contains around 30 species of perennial succulents and evergreen subshrubs from the Crassulaceae family. They are typically stemless or short-stemmed, closely related to the genus Cotyledon. They are easily propagated from leaves - which tend to be rounded, clustered, or spirally-arranged. Five sections are recognised in the genus, based primarily on flowering differences: Adromischus, Boreali, Brevipedunculati, Incisilobati and Longipedunculati. In summer, small, tubular flowers are borne in spike-like structures called cymes.