Ephedra with its jointed, photosynthetic green stems resembles Equisetum

Most species of Ephedra are dioecious On the left are male and male organs Among Ephedra and its relatives Gnetum and Welwitschia, Ephedra is considered to be primitive since its female gametophytes produce archegonia. The other gnetophytes, Gnetum and Weltwitschia, do not develop archegonia; instead, the free eggs are fertilized as in angiosperms.

In the Southwest deserts of the United States, it is called Mormon tea or Brigham tea. American versions of the genus are have also been referred to as "joint fir", due to the jointed stems, nodes, and internodes that resemble the Arthrophyta. In Asia it is referred to as Ma-huang. Ma-huang is first mentioned in the classic Chinese herbal of the Divine Plowman Emporer, Shen-Nong's Ben Cao Jing, which survives a list of 365 herbs from the first century A.D. Used in China for more than 4000 years to treat symptoms of asthma and upper respiratory infections. Varieties of the herb are also grown in Europe, India, Australia and Afghanistan. American ephedra, native to the dry southwest, was used as tea by the early settlers, and was known as "Mormon tea" and "Squaw tea." It has been used in the treatment of headaches, fevers, colds and hay fever. Today, compounds derived from this herb are commonly found in many over-the-counter cold and allergy medications. Ephedra contains two alkaloids, ephedrine and pseudoephedrine. Ephedrine, the main constituent, is a bronchodilator and stimulates the sympathetic nervous system. It has valuable antispasmodic properties, acting on the air passages by relieving swellings of the mucous membrane. Pseudoephedrine is a nasal decongestant and has less stimulating effect on the heart and blood pressure. Physicians use these alkaloids to treat bronchial asthma, bronchitis, emphysema, persistent coughs, wheezing and shortness of breath. Ma huang can help the body to break fevers and clear blocked sinuses. The alkaloids are also effective in treating allergic skin reactions such as hives, relieve general body pain and treat low blood pressure, rheumatism and narcolepsy. Because of its stimulating effect on the nervous system, ephedra can be found in some popular weight loss and energy products. For dieters it suppresses the appetite and stimulates the thyroid gland which stimulates metabolism. Recently ma huang has been the subject of scientific research for obesity because of its thermogenic fat-burning effect on dietary intake. Ephedra can cause peripheral vasoconstriction, elevation of blood pressure and cardiac stimulationand is often combined with other tonic herbs to help counteract these effects.