The Ephedra is one of three genera in the Division Gnetophyta, and bears seemingly little similarity to its relatives, except that they are all resticted in distribution and are not widely cultivated. Only Ephedra is native to the United States, where it grows as a shrub or vine in Texas, New Mexico, Arizona, California, and Nevada, although it has been known to reproduce so far North as Boston, Massachussetts; Marburg, Germany; and Cambridge, England.
At least vegetatively, Ephedra resembles Equisetum, as they both have green stems with minute leaves. Most species of Ephedra are dioecious, and some are called "joint fir." Among Ephedra and its relatives Gnetum and Welwitschia, Ephedra is considered to be primitive since its female gametophytes produce archegonia.
It is also known by other names. If it is sourced in Asia, then it is called by its Chinese name, Ma-huang. Collected from harvests in the Southwest deserts of the United States, it is called Mormon tea or Brigham tea. Ma-huang is first mentioned in the classic Chinese herbal of the Divine Plowman Emporer, Shen-Nong's Ben Cao Jing, which survuves a list of 365 herbs from the first century A.D., and is the basis of the modern Chinese materia medica.