Ephedra is the lone genus in the family Ephedraceae.
There are about thirty species in the genera, which occurs in dry climates
 over a wide area mainly in the Northern Hemisphere,
across southern Europe, north Africa, southwest and central Asia,
south-western North America, and, in the Southern Hemisphere,
in South America south to Patagonia.
The majority of the species are small shrubs, and they are dioecious.