Many edible wild fruits, leafy vegetables, seeds, nuts, root and tuber crops are used as supplementary food sources around the world. They often contribute valuable nutrients to otherwise limited diets. As many are often consumed as snacks between meals, it is sometimes difficult to quantity their importance and contribution. To identify and select species that could qualify for further research and promotion, a 3-step approach (Franzel et al, 1996) can be applied:
1. Creating an inventory of edible wild plant species in a certain region through literature research, semi-structured interviews with inhabitants, where they are asked to name edible species they know of and list their uses, as well as investigation of foraged crops for sale in markets.
2. "Free-listing" (Cotton, 1996), more important crops are identified, if they are mentioned by several interviewees or are mentioned earlier in each list.
3. A sample of informants that seems to be relatively knowledgeable about indigenous foods is then asked to choose and rank their preferred 5 species in regard to their value (taste, caloric or nutritional value, medicinal value, etc.). Data from each informant is then used to calculate a total score and ranking.
Example of wild fruits ranking from Guinea's pre-forest savannahs according to the preferences of the MalinkÉ ethnic group:
