Strophanthus

Strophanthus gratus

Smooth Strophanthus Strophanthus Parts used Uses Habitat and cultivation Constituents

Strophanthus - woody vine climbing to 30 ft (10 m). Strophanthus has elliptical leaves, large yellow to white bell-shaped flowers, and long slender seed pods.

Smooth strophanthus, the plant that yields this two-edged medicinal sword, is a woody climber native to the deciduous forests of tropical West Africa. It ascends to heights of 30 feet or more in a clambering fashion, not twining or supporting itself with tendrils as a true vine does, but using its branches almost as though they were arms to grasp the limbs of supporting trees. Its glossy evergreen leaves are thick and leathery, and it bears terminal clusters of showy, bell-shaped, purple and white flowers that resemble begonias but are fragrant at night with the scent of roses. For these reasons it is often grown as an ornamental in the tropics.

The folk healers of tropical West Africa have found many uses for the plant. They make a rubbing compound from its leaves to reduce fevers; mash the leaves to treat skin ulcerations, wounds, and parasites; and make a decoction of the leaves as a remedy for gonorrhea. But ouabain's (substance obtained from the seed of strophanthus) most common use in its native land has been as a source of arrow poison, both for hunting and for warfare, and it was this use that brought the plant to the attention of Western science.

In 1861 the famed explorer and missionary Dr. David Livingstone observed native peoples hunting with a poison that had been made from the seed of a closely related plant -a true vine called S. kombe-and he later reported the substance as an apparent cardiac stimulant. This led to the investigation of many similar species, of which S. gratus turned out to be the most valuable. (Africans who later heard that the English were using the poison from the seeds in a pure state as a medicine concluded that the English were indeed a mad race.)

Ouabain's fast action is the first quality that distinguishes it from slow-acting, digitalis type heart stimulants. Another is that it does not constrict peripheral blood vessels as digitalis does. However, it is not without its dangers: it cannot be given orally, but must be injected in small, carefully measured doses; it cannot be given to a patient who has suffered recent heart damage; and it cannot be given within a week after a patient has taken digitalis. Within these limitations, it a valuable medicinal weapon, not only against heart disease, but against low blood pressure brought on by anesthesia during surgery.

PARTS USED

Seeds.

USES

Strophanthus may be prescribed like foxglove to treat heart disease, but strophanthus' active constituents are less well absorbed. One authority recommended it as a gentle heart tonic, of particular benefit when combined with valerian and deadly nightshade. Like most herbs containing cardiac glycosides, strophanthus is strongly diuretic.

HABITAT AND CULTIVATION

Strophanthus is native to eastern Africa. Strophanthus grows wild in rainforests and is commercially cultivated. The seeds are gathered when the pod is ripe.

CONSTITUENTS

Strophanthus contains up to 10% cardiac glycosides. These slow the heart rate and improve the heart's efficiency.