The history of water caltrops stretches back thousands of years and is closely tied to agricultural life in ancient Asia. Historical records from China mention them as early as the Han Dynasty, where they were consumed both as food and used in traditional medicinal practices. Farmers would cultivate the plants in natural water bodies, allowing them to grow freely in nutrient-rich environments before harvesting them during late summer and autumn. Fresh caltrops are green or purple and have a soft, watery texture similar to water chestnuts, but they are rarely seen outside their growing regions due to their short shelf life. To preserve them, communities developed drying techniques that transformed the fresh fruit into the hard, blackened pods commonly seen in markets today. This drying process not only extended their usability for months or even years but also concentrated their flavor and made them easier to store and transport. Inside the shell, a white starchy kernel remains protected, waiting to be boiled or roasted into a soft, slightly sweet edible core.
