Sempervivum (Brit. /sɛmpəˈvaɪvəm/, U.S. sem-per-VEE-vum) is a genus of about 40 species of flowering plants in the Crassulaceae family, commonly known as houseleeks. Other common names include liveforever (the source of the taxonomical designation Sempervivum, literally "always/forever alive") and hen and chicks, a name shared with plants of other genera as well. They are succulent perennials forming mats composed of tufted leaves in rosettes. In favourable conditions they spread rapidly via offsets, and several species are valued in cultivation as groundcover for dry, sunny locations.