Ephedra (plant)

Ephedra is a genus of gymnosperm shrubs and the sole living representative of the family Ephedraceae and the order Ephedrales, placing it among the three surviving genera of the division Gnetophyta, alongside *Gnetum* and *Welwitschia*. The genus was first described by Carl Linnaeus in 1753, with *Ephedra distachya* designated as the type species; the family Ephedraceae was later named in 1829. Members of this genus are typically shrubs, though some are clambering vines and rarely small trees, and they often spread through rhizomes. Their stems are green and carry out photosynthesis, while the leaves are opposite or whorled, scale-like, fused into a basal sheath, and usually shed early; most species lack chlorophyll in their leaves, but a few, such as *Ephedra altissima*, produce slender, leaf-like leaves up to a few centimeters long. The plants are mostly dioecious, with male pollen strobili arranged in whorls of one to ten, each with decussate bracts, and the pollen grains are furrowed. Female strobili also grow in whorls, with bracts that fuse around a single ovule; these bracts may be white or red, and each strobilus typically produces one or two yellow to dark brown seeds. The oldest known fossils of the genus date to the Early Cretaceous, about 125 million years ago, from sites in Argentina, China, Portugal, and the United States. However, molecular clock estimates suggest the last common ancestor of living species lived much later, during the Early Oligocene around 30 million years ago, though pollen with modified grooves known from the Late Cretaceous indicates that lineage divergence may be older. The plants are widespread in arid regions across southwestern North America, southern Europe, northern Africa, southwest and central Asia, northern China, and western South America, and in temperate climates they typically grow on shores or in sandy soils with full sun. Common English names include joint-pine, jointfir, Mormon-tea, and Brigham tea; the Chinese name is mahuang. The genus gives its name to the stimulant ephedrine, which the plants contain in significant concentrations.