Map of major oak species and their distribution in South-Western Europe

Oaks (Quercus) are one of the most widely spread type of tree in European forests and their population is made up of diverse species. They are also commonly planted in urban areas.
Once a year, most oak trees produce a nut called an acorn, which contains the seed that allows them to reproduce themselves.
Acorns are edible and can be harvested between September and December depending on the region.
They are high in carbohydrates, proteins, and lipids and contain nutrients such as calcium, iron, magnesium, potassium, phosphorus, vitamins A and E, and unsaturated fatty acids.
In addition to this, they contain varying concentrations of tannins which are very bitter to taste and can cause health problems when consumed excessively.
For this reason, it is important to extract these tannins before using them in food.
Different methods can be used in order to leach the tannins out of acorns, including boiling the in different water consecutively or soaking them in cold water over several days.
On the side, you will find the recipe that made me discover the taste of acorns !

Many animal species already really on acorns as a food resource, but because oaks are not considered fruit or nut trees and are so common around urban areas, they also represent an interesting source of nutrients for human foragers.
Despite appearing only once per year, when stored in properly, acorns can be preserved for several years.
For these reasons, acorns have a potential for becoming a staple food in a money free and fossil free future.