Sources

Edible and useful plants for arid and semi-arid land by the Royal Botanic Gardens, in French, Portuguese, and Spanish as well as English.

A site by Berglund, Bendt, and Clarke E. Bolsby, recommends the following books:

• The Complete Outdoorsman's Guide to Edible Wild Plants, by James A. Duke, published by Charles Scribner's Sons, 1977, New York.
• Handbook of Edible Weeds, by Thomas S. Elias and Peter A. Elias. CRC Press, 1992, Boca Raton.