Njangsa is a fast-growing, buttressed tree of the Euphorbiaceae that is of common distribution throughout tropical West Africa and can reach 50 m height. The tree grows spontaneously from seed and is often preserved near forest villages. It is highly valued for its edible seeds that have high oil and protein content, but more importantly, are popular as a flavouring agent in cooking because of their unique aroma, described as peppery and reminiscent of cocoa. Use of njangsa seems to be particularly popular in Cameroon, and local names for the product appear to have the highest diversity in that country.
Our monograph and extension manual of njangsa, published a few years ago, as well as this undated, but very informative report from Southern Cameroon, seem to be the only comprehensive monographic treatments of this rather important species. You will find there much information on its economic botany, post-harvest processing and uses.
Njangsa fruits are non-dehiscent, so they are generally left in heaps for a few weeks for the pericarp to rot away. The seeds (or “kernels”) are very hard and require prolonged boiling before de-shelling, which involves much drudgery. An improved processing method has been developed by the World Agroforestry Centre but this report is silent on whether it affects the flavour of the product. Simple kernel-cracking machines have also been developed to avoid the tedious task of de-shelling the kernels manually. The dried kernels are traded and fetch good prices. Before use in cooking, they are roasted and pounded into a paste.
Various parts of the njangsa tree are used for medicinal purposes. Its timber is buoyant (similar to balsa). It is easy to carve and used for the resonant parts of musical instruments, and for fetish Kuba masks of the Congo such as the pictured one. There is a bewildering diversity of common names for this species across tropical Africa. We have chosen “njangsa” as this is also the term used in Wikipedia, although differently spelled variants of that “Cameroonian” term seem to be frequent (njansang, ndjanssang, etc.).
A species closely related to njangsa is the mongongo tree (Schinziophyton rautanenii, previously included in genus Ricinodendron), which is common in Southern Africa. It also has edible seeds, which are high in oil and protein content, and have served as a staple to nomadic people in Botswana and Namibia.