Common Name: Yohimbe

General Information

Yohimbe is an evergreen tree producing branches in whorls at its upper end; it can grow from 9 - 30 metres tall. The straight, unbuttressed bole can be up to 50cm in diameter[, , ].
A popular medicinal herb in Africa, where the tree is commonly harvested from the wild for local use as a medicine and source of materials, and is widely sold as a medicine in local markets. It has an ancient reputation in western Africa as a male aphrodisiac and mild hallucinogen, and has more recently gained scientific validation in the West as a treatment for impotency and as a sexual stimulant[, ].

Known Hazards

The bark contains alkaloids that have medical applications at low doses but are toxic at larger doses[]. Poisonous doses of the bark are reported to paralyze respiration and the drug can cause severe hypotension, abdominal distress and weakness[]. The bark can also be used as a fish poison[].

Botanical References

Range

West tropical Africa - Nigeria, Cameroon, Equatorial Guinea, Gabon, Congo, DR Congo..

Habitat

A middle-storey tree of forests[, ]. Occurs mainly in closed canopy forest, most commonly in coastal forest, although not widespread throughout its range[].

Properties

Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	25.00 m
Cultivation Status	Wild

Cultivation Details

A plant of the humid, lowland tropics, where it is found at elevations up to 500 metres[]. It grows best in areas where the mean annual temperature ranges between 22 - 28°c, but can succeed at 18 - 35°c[]. It prefers a mean annual rainfall in the range of 2,000 - 4,000mm, but tolerates from 1,500 - 5,000mm[].
Succeeds in full sun and in partial shade[]. Grows best in a fertile, moist but well-drained, medium to heavy soil with high humidity[, ]. Prefers a pH in the range 5.5 - 7, but can tolerate 5 - 7.5[].
A fast growing tree but the bole never reaches a great diameter[].
The species coppices well, producing strong, highly phototrophic shoots[].
The bark is harvested as the source of the alkaloid yohimbine. The main stem gives the best material but is not rich in alkaloids until the tree is 15 - 20 years of age, by which time it can contain 2 - 15% yohimbine. Bark exploitation is a seasonal activity as the yohimbine levels are highest during the rainy season[].
Although the trees callus well after a small amount of bark removal, removal of large quantities of bark can lead
to an attack by a small stem borer which penetrates the unprotected stem, killing the tree[].

Edible Uses

None known

Medicinal

The bark contains up to 6% of a mixture of indole alkaloids, the principle one being yohimbine (which is also known as aphrodine), plus pigments and tannins[, ]. The alkaloids have a cerebral stimulant action at low doses, but are highly toxic in large doses[]. Yohimbine has been shown to block the release of adrenalin and, in the correct dose, act as a sexual stimulant[]. It is the source of the only clinically-proven cure for impotence and has long been used as a traditional stimulant in Africa[].

Yohimbe is a bitter, warming, anti-diuretic, hypotensive and vasodilating herb with reputedly aphrodisiac effects[]. It has a stimulant effect upon the heart, increasing heart rate and blood pressure; has a locally anaesthetic action similar to that of cocaine but without being mydriatic; is a mild stimulant that can help to prevent drowsiness; and is hallucinogenic. The vasodilating action of yohimbe is particularly strong on the sex organs, hence its aphrodisiac action[, ].
The bark is taken internally, either as a powder or as a decoction. It is used particularly in the treatment of impotence, frigidity and angina[, ]. It is also used as a performance enhancer for athletes, and as a remedy to increase the clarity of the voices of singers during long festivals[, ].
The bark can be harvested at any time of the year[].
The use of this herb is subject to legal restrictions in some countries[, ].

Other Uses

The bark is a source of tannins[].

The inner bark is utilized as straps for panniers[].

The tree produces very little sap-wood, the major fraction being an ocreous-yellow heart-wood[]. The wood is flexible, so is widely used as a snare-trap mechanism, whilst the young poles are used for construction purposes in traditional buildings[].
The wood is used as fuel[, ].

Propagation

Seed -

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