Adam Hochschild’s 1998 best-selling book King Leopold’s Ghost describes King Leopold II of Belgium’s 19th century colony in what is now the Democratic Republic of Congo. Leopold amassed a personal fortune by brutally enforcing a rubber production quota, ironically named the Congo Free State, on the indigenous people of the colony. Rubber was a rare and valuable commodity in Europe in Leopold’s day, and the failure of local people to meet his rubber quota by tapping an indigenous latex-producing vine (Landolphia owariensis) often resulted in having their hands cut off by colonial guards.
By the time Leopold was deposed, the Brazilian rubber tree had taken over the global latex market, and the African gumvine was never cultivated commercially. But in tropical Africa the vine is still tapped for latex to make rubber bands and patch tires, balls, and shoes. More commonly, rural communities harvest the abundant fruits—known as eta—that the vine produces. Planting the eta vine in agroforestry systems and along property boundaries and village common areas could improve food security and income opportunities in impoverished Central and West African communities.
Eta grows wild in tropical Central and West Africa, as a vine in the forest and a shrub in savannah areas. The fruit is reddish-brown with a woody shell and is the size of an orange. The pulp, which has a nice sweet and sour taste, is eaten fresh or squeezed to flavor food or drinks. Although more nutrition research is needed, eta is considered to be very healthy and likely contains high levels of Vitamin A. It is sometimes eaten to aid digestion. A beer is also made from the eta juice. Goat farmers in areas where it grows harvest leaves from the vine in the dry season to use as fodder for their goats.
Fruits and latex are generally harvested from wild eta vines. But intentional planting of the vine with boundary tree rows, on trees planted in crop fields, and on fences, walls, and rooftops would provide a supplemental crop to rural communities. Cultivating the vine in standing forests could help raise the economic value of the forests, reducing the temptation to cut it down for timber or cropland. Many African farmers rotate cultivation plots, leaving some fields fallow for years at a time to allow soil fertility to regenerate. Eta could be grown in these otherwise unproductive fallow areas during the off years. The fruit would provide additional nutritional and excess fruit could be sold for profit. Latex tapped from the vine could be used locally or sold to supply a local latex industry.
Domestication and selection of superior varieties of an eta crop have yet to be attempted. This could be tedious as the vine requires supports, and the rapid, spreading growth makes it hard to manage in an organized way. But some of the world’s major crops—grapes, vanilla, kiwis, and passion fruit, for example—are grown on a vine. Horticultural techniques from those crops could help guide the domestication of eta.
Eta vines are very productive, and as many as 200 fruits have been observed on one vine. In addition, latex can be regularly extracted without harming the crop. A flourishing local industry based on eta cultivation could help Central African communities improve their incomes and food security while preserving forest resources.
By Matt Styslinger