How were water chestnuts introduced?

Question

How were water chestnuts introduced?

Answer 1

Investigations of archaeological material from southern Germany indicate that the prehistoric population of that region may well have relied significantly upon wild water chestnuts to supplement their normal diet and, in times of cultivated cereal crop failure, water chestnuts may even have been the main dietary component. [2]

In the Chinese Zhou Dynasty, water caltrop was an important food for worship. The Rites of Zhou (2nd century BC) mentioned that a worshipper "should use a bamboo basket containing dried water caltrops, the seeds of Gorgon euryale and chestnuts" (加籩之實，菱芡栗脯). The Chinese Herbal Medicine Summary (本草備要 published in 1694, written by Wang Ang 汪昂) indicates that water caltrop can help fever and drunkenness.

It was possible to buy water chestnuts in markets all over Europe until 1880. In northern Italy the nuts were offered roasted, much as sweet chestnuts (Castanea sativa Mill.) are still sold today. At many places in Europe water chestnuts were known and used for human food until the beginning of the 20th century. Today, however, it is a rare plant. There may be several reasons for its near extinction, such as climate fluctuations, changes in the nutrient content of water bodies, and the drainage of many wetlands, ponds and oxbow lakes.[2]

It was introduced to North America around 1874, and escaped cultivation in the eastern United States, where it has become an invasive species from Vermont to Virginia.[3]

In Australia, and its state of New South Wales water caltrop is declared as a noxious weed.

Answer 2

Well I can't compete with Libby..

The only time I buy them is at thanksgiving to add a crunch to my stuffing...  I use up the left overs in my crock pot of soup the next few days after...