Pygeum africanum

Prunus africana, the African cherry, has a wide distribution in Africa, occurring in montane regions of central and southern Africa and on the islands of Bioko, São-Tomé, Grande Comore, and Madagascar. It can be found at 900–3,400 m (3,000–10,000 ft) above sea level. It is a canopy tree 30–40 m in height, and is the tallest member of Prunus. Large-diameter trees have impressive, spreading crowns. It requires a moist climate, 900–3,400 mm (35–130 in) annual rainfall, and is moderately frost-tolerant. P. africana appears to be a light-demanding, secondary-forest species. The bark is black to brown, corrugated or fissured, and scaly, fissuring in a characteristic rectangular pattern. The leaves are alternate, simple, 8–20 cm (3.1–7.9 in) long, elliptical, bluntly or acutely pointed, glabrous, and dark green above, pale green below, with mildly serrated margins. A central vein is depressed on top, prominent on the bottom. The 2 cm (0.8 in) petiole is pink or red. The flowers are androgynous, 10-20 stamens, insect-pollinated, 3–8 cm (1–3 in), greenish white or buff, and are distributed in 70 mm (2.8 in) axillary racemes. The plant flowers October through May. The fruit is a drupe, red to brown, 7–13 mm (0.3–0.5 in), wider than long, two-lobed, with a seed in each lobe. It grows in bunches ripening September through November, several months after pollination. As with other members of the genus Prunus, Prunus africana possesses extrafloral nectaries that provide antiherbivore insects with a nutrient source in return for protecting the foliage. In addition to its value for its timber and its medicinal uses, Prunus africana is an important food source for frugivorous birds and mammals. Dian Fossey reports of the mountain gorilla: 'The northwestern slopes of Visoke offered several ridges of Pygeum africanum .... The fruits of this tree are highly favored by gorillas.' East African Mammals reports that stands of Pygeum are the habitat of the rare Carruther's mountain squirrel and asserts, 'This forest type tends to have a rather broken canopy with many trees smothered in climbers and dense tangles of undergrowth.' It is currently protected under appendix II of CITES since 16 February 1995 and in South Africa under the National Forest Act (Act 84) of 1998. Large numbers of trees are harvested for its bark to meet the international demand for its medicinal qualities. Early studies on the effects of bark harvest showed that the harvest affected population structure, increased mortality and decreased fecundity (Parrott and Parrott, 1989; Cunningham and Mbenkum, 1993; Ewusi et al., 1992; Walter and Rakotonirina, 1995). However, quantitative studies to examine specific life history parameters and possible sustainable harvesting practices were begun only recently (Stewart, 2001 and 2009). In these later studies, the combined factors of mortalities of a large percentage of reproductive trees (especially the largest ones), highly reduced fruit production and poor seedling survival seem to suggest a bleak prognosis for future regeneration and long-term persistence of the species in harvested populations. The species has a long history of traditional uses. The bark is used in an attempt to treat fevers, malaria, wound dressing, arrow poison, stomach pain, purgative, kidney disease, appetite stimulant, gonorrhoea, and insanity. The pharmacology and traditional uses of the species are reviewed in Stewart (2003a and 2003 b) The extract Pygeum is an herbal remedy prepared from the bark of P. africana and is promoted as an alternative medicine for benign prostatic hyperplasia (BPH). Following initial excitement about pygeum's therapeutic potential at the end of the twentieth century, subsequent research has found it to be of no benefit. The timber is a hardwood employed in the manufacture of axe and hoe handles, utensils, wagons, floors, chopping blocks, carving, bridge decks, and furniture. The wood is tough, heavy, straight-grained, and pink, with a pungent bitter-almond smell when first cut, turning mahogony and odorless later.