Common Name: African Nutmeg

General Information

African nutmeg is a large, evergreen tree with a small crown of branches at right angles to the bole; it usually grows from 25 - 35 metres tall, though trees up to 40 metres have been recorded. The bole is usually straight and cylindrical, sometimes with a swollen base or root swelling; it can be unbranched for up to 18 metres, with a bole 60 - 150cm or more in diameter[, , ].
The tree is much used within its native range as a local source of medicines and materials, being commonly harvested from the wild. It is particularly important as a source of a non-edible oil and a good quality wood. The oil is traded locally, whilst the timber is traded internationally[]. It is planted to provide shade in farms and plantations, and is also suitable for ornamental planting[, ]. Pycnanthus angolensis is one of the most important agroforestry tree species of the humid lowland forest of West and Central Africa, and has been identified by the World Agroforestry Centre (ICRAF) as suitable for a domestication programme[].

Known Hazards

None known

Botanical References

Range

Tropical Africa - Senegal to Sudan and Uganda, south to Angola, Zambia and Tanzania.

Habitat

Upland and wet evergreen forest and semideciduous forest, especially abundant in old fallows and secondary forest; riverine and swamp forest in the south of its range. Mostly found in small groups or solitary, at elevations up to 1,400 metres[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	30.00 m
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

A plant of the moist tropics, where it can be found at elevations up to 1,200 metres[]. It grows best in areas where the mean annual temperature is within the range 20 - 28°c, though it can tolerate 15 - 34°c[]. It prefers a rainfall in the range 1,300 - 2,200mm, tolerating 1,000 - 2,600 metres[, ]. The boundaries of the plant's natural range correspond to the minimum rainfall it can tolerate and a dry season of 3 - 5 months[].
Prefers a sunny position, though young plants are more shade tolerant. It succeeds in most soils so long as they are fertile and deep, though it is scace on sandy soils[, ]. Some reports indicate that it is often found on poor soils[]. Plants are intolerant of drought[]. Prefers a pH in the range 5 - 6, though it tolerates 4 - 7[].
In natural stands numerous seedlings appear around the mother tree. In the first year the stem height reaches 20 - 30cm and it can reach 50cm in the second year. In Sierra Leone a mean annual increment in diameter of 16 - 24mm has been observed[].
In good plantations in the evergreen forest zone, the exploitable diameter of 50cm is reached when trees are 30 years old, and a diameter of 60cm at 45 years[].
Because of the long straight trunk, the volume/trunk ratio is higher than in most other African forest tree species[].
Plants can be either monoecious or dioecious[]. If dioecious, both male and female forms will need to be grown if seed is required.

Edible Uses

The seeds are sometimes used as a spice[]. An aromatic flavour[].

Medicinal

The tree provides traditional medicines throughout its range. Various preparations of the bark, and to a lesser extent other parts of the tree, are used. Research has been carried out into the medicinal properties of the plant with promising results.
The oil from the seed contains about 20% kombic acid and sargaquinoic acid, plus several of their derivatives. These terpenoid quinonic acids have promising anti-oxidant properties for pharmacology. They have also shown hypoglycaemic activity in diabetes patients.[].
The bark contains dihydroguaiaretic acid, which has shown non-selective toxicity towards several human tumour cell lines[].
Extracts of the bark have shown the presence of flavonoids, tannins and saponin glycosides, which might be responsible for its biological activities[]. Terpenoid quinones that have shown hypoglycaemic activity in both insulin-dependent and insulin-independent diabetes have been extracted from the bole and leaves[].

The bark is an emeto-purgative, and a decoction can act as an antidote to poisoning; to cleanse the milk of lactating mothers; and also as a treatment for conditions such as coughs and chest complaints, malaria, anaemia, ascites and leprosy[, ]. If pounded, it can be used as a stomachic[]. The bark is also used to treat a number of gynaecological problems, ranging from infertility to gonorrhoea[].
The bark can be used to help relieve the pain of toothache[]. Various preparations of the bark are used to treat skin infections, especially of the mouth[].

The sap is styptic[].

A decoction of the leaves is taken internally and also as an enema to treat dropsy[].
The leaf can be used to help relieve the pain of toothache[].

The oil obtained from the seed, and probably the leaf juice, is used in treating thrush[].

An infusion of the root is used as an anthelmintic[]. A root macerate, mixed with parts of other plants, is taken by draught to treat schistosomiasis[].

Agroforestry Uses:

The tree is often retained when the forest is cleared, and is also planted in order to provide shade for banana, coffee and cocoa plantations[, ].
When growing wild, the tree is condisered to be a good indicator of soil fertility[].

Other Uses

The seeds are pounded and used as a soap substitute[].

The seeds yield 45 - 70% of a yellow to reddish brown oil that is solid at room temperature. Known as 'kombo butter', the taste is bitter and it is not suitable for eating[, ]. It is used in making soap and as an illuminant[, ]. The melting point of the fat is 51°c, the fatty acid composition is 5.5% lauric acid; 61.5% myristic acid; 3.6% palmitic acid; 23.6% myristoleic acid; 5.7% oleic acid. Crude kombo butter contains about 20% kombic acid and sargaquinoic acid, plus several of their derivatives. These terpenoid quinonic acids have promising anti-oxidant properties for cosmetics and the stabilization of plastics[]
The seeds burn like candles[, ].

The heartwood is whitish to pinkish brown, sometimes with yellowish markings; it is not clearly differentiated from the sapwood. The grain is generally straight; the texture medium to coarse; the wood has no lustre; when freshly sawn it has an unpleasant odour which disappears upon drying. The wood is very light to light in weight; very soft to soft; not durable, being liable to attack by termites, powder-post beetles, pinhole borers and marine borers. It is rather difficult to dry, being prone to collapse, end splitting and distortion. The wood is easy to saw and plane with normal tools; blunting effects are moderate; it is difficult to polish; nailing and screwing are easy and holding properties are moderate to good; it splits easily and well. The wood may stain in contact with tools. It peels and slices well to produce good-quality veneer and plywood, although steaming is recommended because of the occasional presence of numerous small hard spots. It glues well with all types of glue; paints well but is rather absorbent. It is used for veneer peeling, panels, furniture frames, box-making, pencils and minor joinery[, , , ]. It is used traditionally to make shingles for the roofs and sides of houses, whilst the long straight bole makes it suitable for making canoes[].
It is used for firewood[]. The wood makes a highly prized fuel[].

Propagation

Seed - it has a short viability and should be sown as soon as it is ripe. Pre-soaking the seed for 24 hours in cold water improves the germination rate. Sow in situ, or in a nursery seedbed in full sun or light shade. Rodents are particularly keen on the seed, so it needs protection. Germination of soaked seeds can be 100%, with the seeds sprouting within 16 - 36 days. The cotyledons are pulpy and the first two leaves which appear after two months are simple, opposite or alternate, later leaves alternate. A deep secondary root system develops during the first seven months of growth and may need checking in nursery-grown plants[]. It is advisable to transplant nursery-grown seedlings after 1 - 2 years when 30 - 50 cm tall, at the beginning of the rainy season[].
Cuttings do not thrive[].

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