An interesting article appears in the Bulletin of the Imperial Institute, vol. xviii., No. 2 (1920), entitled “The Cultivation of the African Oil Palm, with special reference to the East Indies.” From this it appears that the tree thrives and yields very satisfactorily, especially in Sumatra; the oil content of the fruit and kernels being both high. Attention is drawn in this article to the extension of the use of palm oil in Europe as an edible fat, in addition to its present uses.
Other Oil Seeds.—Excluding the shea nut tree, which will be referred to later on, three trees have been considered of sufficient importance for their seeds to be shipped to Europe in order that their value may be determined. These are Pentaclethra macrophylla (Cutlass bean), Irvingia Barteri (African mango), and Lophira alata. Although the trials proved that the oils of all might be valuable for the manufacture of soap and candles, none of the trees occur in sufficient profusion to permit a large export trade in the seeds being established. (See Bulletin of the Imperial Institute, vol. v. [1907], pp. 10-14, and vol. vi. [1908], pp. 243, 354-80.)
RUBBER.—Following the progress made by the Forestry Department in re-establishing the indigenous rubber tree (Funtumia elastica) in places from which it had almost disappeared, an excellent system of communal plantations was established. This system, which has been largely adopted by the chiefs, is one to encourage the village inhabitants to re-establish rubber trees in their proximity; the planting and tapping and preparation of the rubber being under the direction of the Government officers. The resulting rubber is marketed by the Government, who retain one-third of the sale price to cover the cost of supervision, etc.; the remaining two-thirds being paid to the village community. In this manner a large number of communal plantations have now been established. In 1911 over 400 new plantations of this kind were made; about 100,000 Funtumia plants being put in. At the same time 129,000 Para rubber seeds and some 4,000 seedlings were distributed under the same scheme, while Ceara plantations were made in the drier parts of the country. Licences to collect wild rubber were simultaneously made compulsory.
The rubber produced on the Government plantation at Mamu Forest, by the boiling method, proved very satisfactory. In 1910 such rubber was sold at 6s. 6d. per lb., being only 6d. less than the best Para fetched at the same time. Three hundred communal plantations yielded rubber in 1911 against eighty-four in the previous year, the average yield per tree being 1·59 oz. against 1·406 oz. In 1912 communal rubber amounted to 3,031 lbs., which sold at about 3s. 4d. per lb.; and in the same year Government plantation rubber was 3,501 lbs., which realised 3s. 10d. per lb.
The next rubber plant of importance is the vine, Landolphia owariensis, which is somewhat variable in the form of growth. The latex at certain seasons coagulates almost instantaneously, but at other times it runs freely, and can be collected for coagulation by heat, the admixture of acid, alkali or alcohol, or by spontaneous exposure. The scrap rubber, which is collected from that coagulated upon the stem, is made into balls, and comes into the market under the name of “first Niggers,” and commands a high price.
The native has discovered that a larger amount of rubber can be obtained at one time if the roots and stems are cut and pounded up. The result is a product known as “root rubber,” the collection of which can be justified only where the plant, from which it is obtained, develops an extensive rhizome or subterranean growth, capable of being partially removed without killing the plant. Such vines, although found in some other parts of Africa, do not occur in Southern Nigeria, and the collection of so-called “root rubber” from L. owariensis only leads to the complete destruction of the plant, and should be discouraged. The small yield of latex from this species after many years of growth, and the difficulties in connection with the collection of the rubber, render its cultivation in plantations unprofitable, although planting has been attempted in the French and German Colonies.
Clitandra elastica is another vine said to yield a copious supply of latex, capable of being coagulated by means of heating after dilution with water. In appearance the vine is somewhat similar to L. owariensis, but does not appear to be common. The rubber produced from this species is reported to be of excellent quality.
Carpodinus hirsutus, a common vine in the dry zone and on the Niger river banks, furnishes a plentiful supply of latex of inferior quality, and is made into “root” and “paste” rubber by boiling; the latter being a sticky product of the consistency of birdlime, and only saleable in Europe at a low price.
The latices of Landolphia Thompsonii and L. senegalensis are used similarly. Both species are nearly allied to L. florida, which is prepared elsewhere.
A number of latex-yielding plants are employed in the adulteration of good rubber, among which the following may be mentioned as the commonest: Funtumia africana, Conopharyngia sp., Alstonia congoensis, and Holarrhena Wulfsburgii. The admixture of these is usually detected by the stickiness which they impart to good rubber.