The Crassulaceae, also known as the stonecrop family or the orpine family, are a diverse family of dicotyledon flowering plants characterized by succulent leaves and a unique form of photosynthesis, known as Crassulacean acid metabolism (CAM). Flowers generally have five floral parts. Crassulaceae are usually herbaceous but there are some subshrubs, and relatively few treelike or aquatic plants. Crassulaceae are a medium size monophyletic family in the core eudicots, among the order Saxifragales, whose diversity has made infrafamilial classification very difficult. The family includes approximately 1,400 species and 34–35 genera, depending on the circumscription of the genus Sedum, and distributed over three subfamilies. Members of the Crassulaceae are found worldwide, but mostly in the Northern Hemisphere and southern Africa, typically in dry and/or cold areas where water may be scarce, although a few are aquatic.
This iis a family of morphologically diverse terrestrial perennial, rarely annual or hapaxanthic (flowering once in a lifetime), flowering plants that demonstrate xerophytic adaptations, with thick succulent leaves, a thick waxy cuticle and Crassulacean acid metabolism. Crassulaceae are generally herbaceous but there are some subshrubs, and relatively few treelike, epiphytic (growing on surface of plants), scandent (vine like) or aquatic plants. Most species are herbaceous leaf succulents, with regular 5 part (pentamerous or fivemerous) flowers, isomerous free carpels and one or two whorls of stamens.
Stems are sometimes succulent, as may also be the underground caudices (rootstock), and may form rhizomes or corms. Bulbils may form along the stem or leaf margins. The leaf arrangement is opposite and decussate or alternate and spiral, and they are frequently aggregated into rosettes. The leaf shape is simple (rarely pinnate) and usually entire, or crenate to broadly lobed, sometimes dentate or more deeply incised, glabrous (smooth) or tomentose. In cross section the leaf blades are flat or round. They may be sessile or petiolate. Stipules are absent. New plants often form easily from vegetative parts that fall off the parent plant.
The inflorescence is usually terminal to lateral with many-flowered thyrses of cymes, less commonly spikes, racemes or panicles, rarely few to single flowered and axillary. The inflorescence is often many-branched and bracteate. The flower clusters are red, yellow, or white.