Cacti: Biology and Uses - Google Books

https://books.google.de/books?id=DISMqbY-igwC&pg=PA23#v=onepage

The Cactaceae family, with about sixteen hundred species, is cultivated worldwide for fruits, forage, fodder, and even as a vegetable. Cacti are recognized for their attractive flowers, special stem shapes, and ability to tolerate drought. Because of their…