Botany Department

About 30 genera and 1,500 spp. of annual to mostly perennial, succulent herbs and shrubs, widely distributed in both hemispheres. Crassulacean acid metabolism (CAM), a type of photosynthetic adaptation to high light and low moisture environments, was first described for the stonecrop family. It is a mechanism in which the stomates open at night (unlike most plants) to allow the accumulation of carbon dioxide in the form of an organic acid and the stomates close during the day, when the stored carbon dioxide is used in photosynthesis. Leaf Succulents like sedum morganianum (Burro's-tail) and Crassula argentea ( Jade Plant) have adapted to dry habitats, by evolving "chunky" leaves or stems to reduce their surface areas relative to their volumes or like Kalanchoe tomentosa, a leaf succulent from Madagascar, which has dense white hairs and thereby reduces the rate of transpiration. The spectacularAeonium tabuliforme, primarily from the Canary Islands (Macaronesia), is a good example of island plants that become woody.