Rank Species | Subtribe Plukenetiinae | |
Similar Plukenetia, Coula edulis, Njangsa, Ricinodendron, Monodora myristica | ||
Plukenetia conophora, also called Nigerian walnut, and conophor, is a climbing shrub in the genus Plukenetia. It is not related to the walnut, being so named because its nuts bear a superficial resemblance to the walnut. It is native to tropical western and central Africa from Togo to Congo and in Sierra Leone. It is abundant in the Nigeria, Cameroon, Republic of the Congo and Democratic Republic of Congo. It prefers rain-forest hedge in half-shady places; low bush; secondary forest; plantations at elevations from 250–1,400 m (820–4,590 ft) Although it is well recorded in Sierra Leone, it is apparently not indigenous to Sierra Leone, since it is not recorded in Liberia and Ghana. Its presence in Sierra Leone is due to returning slaves for it is known to the Krio by its Yoruba (Nigerian) name. Plukenetia conophora is the only Plukenetia species native to West Africa or Central Africa. Others Plukenetia species are indigenous to other parts of Africa, the Indian Subcontinent, Southeast Asia, and America.
Contents
Morphology
It produces stems usually 3–15 m (9.8–49.2 ft) long, though they can be up to 30 m (98 ft) long. The seed is thin-shelled and about 25 mm (0.98 in) long.It is contained in a pod which may house;one shelled nut (single), two shelled nut (double) and three shelled nut. The walnut shells could be black or brown from the plant. The nut is whitish upon cracking from the shell. The nut has a thin layer in between two halves (when a nut is divided into two equal parts) of nut.
Botany
The Nigerian walnut (Plukenetia conophora) belongs to the family Euphorbiaceae in the order Malpighiales of angiosperms in the plant kingdom. Euphorbiaceae is a large family of flowering plants with about 300 genera and 7,500 species. Members of the family are generally called spurge. This family occurs mainly in the tropics, with the majority of the species in the tropical America and Indo-Malayan regions. A large variety occurs in tropical Africa, but they are not as abundant or varied as in the two other tropical regions. However, Euphorbiaceae also has many species in nontropical areas such as the Mediterranean Basin, the Middle East, South Africa and southern USA. Of the three subfamilies of Euphorbiaceae – Acalyphoideae, Crotonoideae and Euphorbioideae; only Acalyphoideae is native to Africa.
The genus Plukenetia (Euphorbiaceae) is a pantropical genus of 19 species belonging to the tribe Plukenetieae of the subfamily Acalyphoideae Three sections or species groups of genus Plukenetia have been recognized. The two previously named genera, Tetracarpidium (synonym Angostylidium) and Hedraiostylus (synonym Pterococcus), are now treated as sections of Plukenetia. The monotypic Plukenetia sect. Tetracarpidium (Angostylidium) includes the African species Plukenetia conophora, while Plukenetia sect. Hedraiostylus (Pterococcus) comprises two African species (Plukenetia africana and Plukenetia procumbens) and one Asian species (Plukenetia corniculata). A third species group restricted to Madagascar comprises three species; Plukenetia madagascariensis, Plukenetia deciduas and Plukenetia ankaranensis. However, Plukenetia conophora is still, in some literature, erroneously referred to by the genus Tetracarpidium.
Usage and Ethnomedicinal claims
Plukenetia conophora is widely cultivated for its nuts, which are cooked and consumed as snacks; often served with corn or rice. The importance of Plukenetia conophora as an indigenous fruit climber is enormous as it is a multipurpose crop. In West Africa, especially in Nigeria, Sierra Leone and Central Africa, Cameroon, the seeds provide income to the rural people thereby improving their economy. Eaten boiled, it has a bitter after taste usually observed upon drinking water. The seed can be ground into a powder and used with flour in making cakes. The nuts, leaves, root and stem bark of Plukenetia conophora has been used in tradition medicine and folklore for the therapy of many ailments. In Gabon, consumption of the seeds by husbands of pregnant women is believed to mitigate the risk of miscarriage. This has led to propositions that the nut boosts male fertility or has aphrodisiac potentials. This is partially justified by the use of the nuts for boosting male fertility and increasing libido in western Nigerian traditional medicine. The nuts are also believed to tonify kidneys, strengthen the back and knees, and moisten the intestines. It is also alleged to stop asthma, and is prescribed to be taken between bouts of asthma, but not for acute asthma.
The nut, eaten raw, has a bitter taste comparable to that of kola nut and is considered tonic. The fresh nuts are used as snake antivenin. The nuts can also be roasted and eaten in the general diet, or added to cakes. The nuts are oil-bearing yielding 48–60% of a light golden coloured oil with a taste resembling linseed oil. The oil is edible, although it not suitable for frying or soap manufacture, due to its quick drying property. The oil has thus been found useful in the formulation of wood vanish, stand oil, vulcanized oil for leather and rubber substitute.
The leaves are also edible and are often eaten with rice. Like the nuts, the leaves, bark and root of P. conophora are considered medicinal. The leaves are used in the treatment of indigestion, constipation, diarrhoea, dysentery, syphilis, thrush, intestinal worm infection, asthma, prolonged and constant hiccups, eczema, pruritus, psoriasis and parasitic skin conditions mostly among children, the elderly and immunosuppressed. The leaves are also used traditionally for curing headache in the southwest Nigerian traditional medicine. Juice from the leaf is use for the treatment of prolonged and constant hiccups. The stem bark is used as tea for laxative and chewed for toothache. The stem bark is also believed to reduce blood pressure. The root of is used in Nigerian traditional medicine for the treatment of cancer (Engel et al., 2011). The root is also macerated and used in the treatment of asthma and hypertension.