Cyperus is a large genus of about 600 species in the Cyperaceae family native throughout all continents in both tropical and temperate regions. They are annual or perennial plants, mostly aquatic and growing in still or slow-moving water up to 0.5 m deep. Some grow from rhizomes and some from tubers. Several are used for food (tubers, pith of young plant stems).
Cyperus esculentus L., commonly known as earth almond, chufa or tiger nut, is a common food crop in Southern Europe and West Africa. The exact origin is unclear, as is common with long term cultivated plants. The species is spreading world wide as a sometimes aggressive neophyte via seeds in subtropical climates, but can also be spread vegetatively with agricultural equipment in temperate regions, where it usually doesn't flower or at least doesn't form viable seeds. Populations have reached up as far north as Germany, Poland and the Ukraine, likely expanding the territory as winters get milder. Cultivation requires good watering, but far less than common in the genus, and warm soils. It is recommended to plant them after soil temperature reaches 12 °C. Nitrogen fertilizer actually reduces yield.
The tubers have a mild and sweetish nut flavour, for Martin Bohnet closer to hazelnuts than almonds. The photos below show the one year increase, in the single pot shown above. The cultivar shown is "Giant from Ghana", though it is unclear if it can reach its full size in middle European conditions.
