Chinese watercress is one name for Ipomoea aquatica, also known as water spinach, swamp cabbage, on-choy, swamp morning glory and several other names. This is a fast-growing flowered vine that covers the surface of bodies of water. Chinese watercress is a cultivated food known for having a substantial vitamin A and iron content in Asia and other parts of the world including South America. It is also used for animal and fish feed. Chinese watercress is not the same as the watercress sold in markets in countries like the United States, which is a member of the Nasturtium genus. Ipomoea aquatica is related to sweet potatoes and is part of the Convolvulaceae, or morning glory, family.
The vines and leaves of Ipomoea aquatica are green, and the flowers are white with purple centers. The stems are hollow, so the vines float on top of water. Rapid growth of almost 4 inches (10.16 cm) a day allows the plant to choke bodies of water, making it difficult for any other life to survive because of the lack of light and the competition for nutrition and space. The total length of the plant can be almost 13 feet (4 m).
While many countries are able to control and cultivate the vegetable, it has become an invasive pest plant in other countries such as the United States. In fact, it is illegal in some regions to sell the plant for fear of its escaping and contaminating local waters. Other areas require government permits to grow the plant.
A warm, humid climate is essential for the plant’s growth, so it is not a problem in more northern areas. Those areas further south, however, like the US state of Florida, have had to combat the plant as it springs up repeatedly and is difficult to control. Its dense growth promotes conditions in which mosquitoes may breed, creating a secondary threat.
Edible parts of Chinese watercress include the leaves, shoots and stems. The different dishes that use Chinese watercress range from African salads, porridge and stew to Asian stir-fries mixed with other vegetables, noodles or just garlic and soy sauce. Chinese watercress is edible when raw, although parts of the stem may leak white sap.