Description

A large tree reaching 35 m height in the western part of the Region, but less in the east, high buttresses, sometimes to 6 m, straight bole to 1 m diameter, less in the East, slightly fluted, carrying a dense compact crown, of the evergreen dense rain-forest from Senegal to W Cameroons, and widely dispersed from Sudan to Uganda and Angola (15, 16, 20–22).Forms are recognised by Africans. In Liberia there are two: one small-leaved with inedible seeds, and the other larger-leafed and edible seeds (22). In Nigeria var. gabonensis has sweet edible fruit-pulp, and var. excelsa (Mildbr.) Okafar has bitter inedible pulp but is slimy and is added to soup for this quality (17). In Lower Dahomey a variety with a thick edible pulp is cultivated (12, 14). In Ivory Coast large-leaved and small-leaved forms are given separate vernacular names, the former being considered inedible, which differences on taxonomic standards, however, appear untenable (3). Nevertheless, the distinction between edibility and inedibility is of basic pragmatic importance, and this and other distinctions recognised by countrymen in the field merit serious study to gain a proper understanding. In Igalaland (Nigeria), as no doubt elsewhere, it is considered one of the most important trees of the bush, and individual Igala lay claim to the produce of a tree by farming around it or by clearing the land beneath (26).Sap-wood is light brown, and heart-wood a slightly darker or greenish-brown (11, 15, 16, 20, 21). The wood is very hard, and not easy to cut limiting its usefulness where only simple implements are available. It is very heavy and durable, but its weight is said to preclude it from all but the most rugged construction-work, e.g., for railway-ties, etc. (8, 22). It is immune to termite attack and is used for house-building. Canoes can be made from the trunk, and pestles for yam-mortars. There is a fine moderately close grain and a good polished finish can be achieved. It is suitable for boards, planking, ships’ decking, paving blocks, and the like (11–13).Tests for paper manufacture have shown cellulose content 48 .8%, fibre length 1.5 mm, and the resultant dark brown paper to be inferior, rather weak and soft, and not bleachable (8, 10).The bark-slash is brown with lighter brown to orange-yellow stripes or spots. A small amount of clear sap is expissated (20). This is said to be sweet (21) though the bark itself is bitter and has the usual usages of bitter barks: in Sierra Leone it is ground up with water for rubbing on to the body for pains (12); in Ghana it is used in an enema for an unspecified purpose (15); in Gabon it is added to palm-wine to increase potency (12), and scrapings are taken in a baked banana or prepared in enemas to relieve diarrhoea and dysentery (24); in Congo (Brazzaville) the bark has use in mouth-washes for toothache, pulped on sores and wounds, internally as a purgative for gastro-intestinal and liver conditions, for sterility, hernias and urethral discharge, and is considered by some to be a powerful aphrodisiac and to be beneficial in cases of senility (4).Tannin has been reported present in both the bark and the roots (5), also a strong presence of alkaloid in the bark, though none in the roots (1). Root and wood extracts have proved ineffective in avian malaria (9), though Igbo use a leaf-decoction as a febrifuge (28). A wax has been extracted from the plant which has been found useful as an adjunct in making medicinal tablets (27).As already indicated above, the fruit is variable, with special forms. It is the most important part of the tree. It is a drupe, resembling a mango, with a fibrous pulp surrounding the hard-shelled nut. The pulp of some trees is edible with a turpentine flavour, and of others inedible, bitter and acrid. The edible ones are a source of vitamins (18). In the forest animals readily search out the fruit for the pulp, but the seed is protected by its hard endocarp (21). The pulp is used at Lagos to prepare a black dye for cloth (21).The kernel is an important source of vegetable oil. In season the fallen fruits are collected in the forest and stacked till the pulp has rotted away. The nuts are opened and the cotyledons removed and dried. The cotyledons are a common item of market produce and are used in soups and as a food flavouring. They are said to have a pleasant taste with a lingering slight bitterness. They are rich in oil, but there is a wide variation in quantity and composition; even so they are considered a suitable source of industrial and edible oils. Total fat content has been recorded as 54–68% and a series of five analyses from Nigeria (in brackets) and central Africa gave the following assays: lauric acid 0–39 (39) %; myristic 31–69 (51) %; oleic 0–22 (10) %; stearic 0–4 (0) % and palmitic 0–65 (0) % (2, 7). The principal domestic use is for the preparation of odika, or dika bread, also known as Gabon chocolate. For this the cotyledons are ground and heated in a pot, lined with banana leaves, to melt the fat, and then left to cool. The resultant grey-brown greasy mass is dika bread. It has a slightly bitter and astringent taste with a more or less aromatic odour. Pepper and other spices may be added, and it may perhaps be subjected to woodsmoke. The end product may be made up into cylindrical packets wrapped in a basket-like or leaf-wrapping. It can be kept for a long time without going off and it is used as a food-seasoner (3, 6, 12, 14, 15).An alternative method of preparation, more akin to the making of vegetable butters, is to take the fresh or stored cotyledons and pound them into a paste. This can be done in quantities according to the immediate requirement. A third preparation, known in Gabon as ovéke, is to soak the kernels for 15–20 days till soft and then to knead them by hand into a cheese-like paste (3, 7, 12, 14, 15, 23, 24). A fourth practice is known in Sierra Leone, in which the cotyledons are dried and ground to a brown ‘flour’ in which form it can be stored for use as an additive to food as and when required (19). The crude dika paste yields on heating or boiling 70–80% of a pale yellow or nearly white solid fat, dika butter, which has qualities comparable with cacao-butter, and is, in fact, a possible adulterant or substitute for the latter in chocolate manufacture. Freed from its slight odour it can also be regarded as suitable for margarine manufacture. It is also suitable for soap-making (12).Following processes in which the fat is removed the residual cake, rich in protein, is a cattle feed-stuff similar to copra cake. The following composition is recorded, crude protein 31%, fat 10%, carbohydrate 39%, fibre 3% and ash (minerals) 6% (25).In Nigeria and Cameroon the split shells of the fruit are used in divination — if one falls convex side up and the other in reverse, the omens are good (12).