Ephedra (plant)


Ephedra is a genus of gymnosperm shrubs, the only genus in its family, Ephedraceae, and order, Ephedrales. The various species of Ephedra are widespread in many lands, native to southwestern North America, southern Europe, northern Africa, southwest and central Asia, northern China and western South America.
In temperate climates, most Ephedra species grow on shores or in sandy soils with direct sun exposure. Common names in English include joint-pine, jointfir, Mormon-tea or Brigham tea. The Chinese name for Ephedra species is mahuang. Ephedra is also sometimes called sea grape, a common name for the flowering plant Coccoloba uvifera.
pollen cones
: ripe female cones with seeds
'' seed

Description

The family, Ephedraceae Dumort., of which Ephedra is the only genus, are gymnosperms, and generally shrubs, sometimes clambering vines, and rarely, small trees. Members of the genus frequently spread by the use of rhizomes.
The stems are green and photosynthetic. The leaves are opposite or whorled. The scalelike leaves fuse into a sheath at the base and this often sheds soon after development.
There are no resin canals.
The plants are mostly dioecious: with the pollen strobili in whorls of 1-10, each consisting of a series of decussate bracts. The pollen is furrowed. The female strobili also occur in whorls, with bracts which fuse around a single ovule. There are generally 1-2 yellow to dark brown seeds per strobilus.

Distribution

The genus is found worldwide, in desert regions, but not in Australia

Ecology

Ephedraceae are adapted to extremely arid regions, growing often in high sunny habitats, and occur as high as 4000 m above sea level in both the Andes and the Himalayas.

Taxonomy

The genus, Ephedra was first described in 1753 by Linnaeus, and the type species is Ephedra distachya. The family, Ephedraceae, was first described in 1829 by Dumortier.

Medical uses

Plants of the genus Ephedra, including E. sinica and others, have traditionally been used by indigenous people for a variety of medicinal purposes, including treatment of asthma, hay fever and the common cold. The alkaloids ephedrine and pseudoephedrine are active constituents of E. sinica and other members of the genus. These compounds are sympathomimetics with stimulant and decongestant qualities and are chemically substituted amphetamines.
Pollen of Ephedra spp. was found in the Shanidar IV burial site in Iraq, which led to the suggestion that its use as a medicinal plant dates to over 60,000 years ago. Paul B. Pettitt has stated that " recent examination of the microfauna from the strata into which the grave was cut suggests that the pollen was deposited by the burrowing rodent Meriones persicus, which is common in the Shanidar microfauna and whose burrowing activity can be observed today". It has been suggested that Ephedra may be the soma plant of Indo-Iranian religion.

Adverse effects

Alkaloids obtained from the species of Ephedra used in herbal medicines, which are used to synthetically prepare pseudoephedrine and ephedrine, can cause cardiovascular events. These events have been associated with arrhythmias, palpitations, tachycardia and myocardial infarction. Caffeine consumption in combination with ephedrine has been reported to increase the risk of these cardiovascular events.

Species

Accepted species:
Earliest uses of Ephedra spp. for specific illnesses date back to 5000 BC. Ephedrine and isomers were already isolated in 1881 from Ephedra dystachia and characterized by the Japanese organic chemist Nagai Nagayoshi of the 19th century. His work to access Ephedra drug materials to isolate a pure pharmaceutical substance, and the systematic production of semi-synthetic derivatives thereof is relevant still today as the three species Ephedra sinica, Ephedra vulgaris and to a lesser extent Ephedra equisetina are commercially grown in Mainland China as a source for natural ephedrines and isomers for use in pharmacy. E. sinica and E. vulgaris usually carry six optically active phenylethylamines, mostly ephedrine and pseudoephedrine with minor amounts of norephedrine, norpseudoephedrine as well as the three methylated analogs. Reliable information on the total alkaloid content of the crude drug is difficult to obtain. Based on HPLC analyses in industrial settings, the concentrations of total alkaloids in dried Herba Ephedra ranged between 1 and 4%, and in some cases up to 6%.
For a review of the alkaloid distribution in different species of the genus Ephedra see Jian-fang Cui. Other American and European species of Ephedra, e.g. Ephedra nevadensis have not been systematically assayed; based on unpublished field investigations, they contain very low levels or none at all.