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Watercress

life science Maturity 5-7 Next article →

Watercress, known scientifically as Nasturtium officinale, is a fast-growing perennial aquatic plant. It belongs to the Brassicaceae family, which is commonly called the cabbage family. This plant is highly significant because it is one of the oldest leaf vegetables consumed by humans. While its Latin name suggests a connection to the flowers called nasturtiums, they are actually different. Nasturtiums belong to the Tropaeolaceae family. Molecular evidence shows that watercress with hollow stems is actually more closely related to the genus Cardamine than to the genus Rorippa.

WarnfordWatercress
WarnfordWatercress

The physical structure of watercress allows it to thrive in its watery environment. The plant features stems that are hollow, which helps them float in the water. Its leaf structure is described as pinnately compound. When the plant matures, it produces small inflorescences, which are flower clusters. These clusters are white and green in color. These flowers attract various insects, particularly hoverflies such as Eristalis flies. If left unharvested, the plant can grow to a significant height.

WarnfordWatercress
WarnfordWatercress

Watercress grows best in specific natural habitats. In the United Kingdom, it prefers clear, fast-flowing chalk streams. These streams provide water that is slightly alkaline, which is the ideal condition for the plant. Because it is a semi-aquatic plant, it is very well-suited for hydroponic cultivation. This is a method of growing plants in water rather than soil. In some regions, watercress is considered a weed. When it is introduced to non-native environments, it can become invasive. It increases organic matter in the sediment, which attracts predatory macroinvertebrates that eat other native plants. For this reason, it is prohibited in Illinois.

WarnfordWatercress
WarnfordWatercress

The history of watercress cultivation is quite long. In the United Kingdom, the horticulturist William Bradbery first began commercial cultivation in 1808. He grew the plant along the River Ebbsfleet in Kent. Since then, cultivation has spread to many areas. In the 1800s, watercress was introduced to China via Hong Kong and Macao. It also spread to the tropical highland areas of Asia. In England, many settlements carry names derived from the Old English word for watercress, such as Kersey and Kershopefoot. Even the famous Watercress Line railway was named after the plant because it was a common cargo.

WarnfordWatercress
WarnfordWatercress

Cultivation is done on both large and small scales. In the UK, important historical sites include Hampshire, Stamford, and St Albans. Today, it is grown in counties like Dorset, Wiltshire, and Hertfordshire. New Alresford in Hampshire is known as the nation's watercress capital. Growing it hydroponically is common because it meets high market demand. However, fresh watercress is difficult to distribute. This is because the leaves cannot be dried and stay fresh for only two to three days. Some people also harvest the edible shoots as sprouts shortly after germination.

WarnfordWatercress
WarnfordWatercress

Watercress is a very nutrient-dense food. It is composed of 95% water, 2% protein, and 1% carbohydrates. It contains negligible amounts of fat. A reference amount of 100 grams of raw watercress provides 11 calories of energy. It is a rich source of vitamins, providing 208% of the Daily Value (DV) for vitamin K and 48% DV for vitamin C. It also contains moderate amounts of vitamin A, manganese, and potassium. People eat the leaves, stems, and fruit. In China, it is boiled with pork for a wintertime tonic soup. In Vietnam, it is often used raw in salads.

WarnfordWatercress
WarnfordWatercress

Throughout history, people have used watercress for many different purposes. Ancient Romans believed it could cure mental illness. In the twelfth century, Hildegard of Bingen suggested steaming it to treat jaundice or fever. Native Americans used the plant to treat constipation and kidney illnesses. Some also thought it was an aphrodisiac. Early African Americans used it as an abortifacient. From a modern medical perspective, certain compounds in watercress may cause drug interactions. Specifically, they may inhibit the cytochrome P450 enzyme CYP2E1. This could affect people taking medications like chlorzoxazone. When collecting wild watercress, one must be careful of parasites like giardia or the liver fluke, Fasciola hepatica.

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