It was possible to buy water caltrops in markets all over Europe until 1880. In northern Italy, the nuts were offered roasted, much as sweet chestnuts ("Castanea sativa") are still sold today. In many parts of Europe, water caltrops were known and used for human food until the beginning of the 20th century. Today, however, it is a rare plant. Several reasons for its near extinction exist, such as climate fluctuations, changes in the nutrient content of water bodies, and the drainage of many wetlands, ponds, and oxbow lakes.