Ephedra plant. Ephedra plant (Ephedra americana) growing by a rock. This plant is a source of the drug ephedrine, a nerve stimulant similar to adrenaline. Preparations can be used to treat asthma, hay fever and rheumatism. It also has antispasmodic properties, and can be used to raise blood pressure. It grows throughout North America, although related species are found all over the world, and have been used for centuries.