The characteristic taste of watercress is due to the mustard oils it contains. As a marsh and water plant, watercress grows best on and near water. Its hollow shoots can reach a length of up to 80 centimeters, and it has round leaves that grow on both sides of the stem (pinnately compound leaf structure). Watercress stimulates metabolism and is considered a natural antibiotic. In cooking, it can be used to season a wide variety of cold and warm dishes.
Watercress has a spicy to slightly bitter taste and gives salads and raw vegetables a tangy, peppery flavor. Along with the leaves and stems, the roots, seeds, and blossoms can also be eaten raw. Since watercress has such an intensive flavor, it is best not to use it in combination with other spicy ingredients. It goes well with fruits such as apples and oranges and is a nice addition to marinades, potato dishes, and steamed vegetables. Watercress soup served with mashed potatoes is considered a delicacy. Finely chopped, the leaves can be added to pestos, green smoothies, herb sauces, or spinach. The leaves and flowers can be used as a decorative garnish. In the past, watercress seeds were used in breads, as pepper salt, and ground into mustard.1,2
Watercress grows best along chalk streams (wide and shallow streams that are clear and alkaline). The green shoots float on the surface of the water and can spread to form a carpet-like covering. Watercress can be gathered from clean bodies of water in the springtime; it is best to transport them in a bag or bucket with water to preserve the flavor. Before using, you should wash the leaves well as insect larvae or cysts of the liver fluke can adhere to them.1 The leaves and white flowers can be harvested from May to October and the seeds can be harvested starting in September.2
To grow watercress at home, it is best to pot it in a mixture of sand, garden soil, and compost. It is also important to make sure that watercress, an aquatic plant species, always has a source of fresh, oxygen-rich water. If you want to plant it in the garden, clay soil is most suitable because it retains moisture well. Since watercress needs light to germinate, gently press the seeds in the soil without covering them with soil. However, watercress should not be planted in direct sunlight as it thrives in semi-shaded areas. Watercress can be harvested as soon as it has reached 10 centimeters.3
Watercress can be stored at room temperature for only one day. However, you can store it in the refrigerator (3 to 5 °C) wrapped in plastic for a week.4
Watercress is 95 % water and supplies the body with flavonoids, iodine, and minerals such as calcium and iron. In addition, it is a good source of several vitamins including vitamins A, K, B2, and C. The characteristic taste of watercress is due to the mustard oils (glucosinolates) it contains.1,2
Fresh watercress acts as a diuretic, promotes digestion, and stimulates metabolism. In addition, the mustard oils (glucosinolates) have properties of a natural antibiotic. There is also evidence that watercress possesses anticarcinogenic effects.1, 2 Studies have shown that watercress juice provides a high level of protection against benzo(a)pyrene-induced DNA damage in human cells.5 Benzo(a)pyrene, which is only transformed into a toxic substance once in the body, is one of the longest known and most studied carcinogenic substances.6
In traditional medicine, watercress is used in the treatment of catarrhs, urinary tract diseases, and skin diseases as well as to promote bile secretion and support inflammatory processes in the mouth and throat.2
From Wikipedia: Watercress is an aquatic plant species with the botanical name Nasturtium officinale. This should not be confused with the profoundly different and unrelated group of plants with the common name of nasturtium, within the genus Tropaeolum.
Watercress is a rapidly growing, aquatic or semi-aquatic, perennial plant native to Europe and Asia, and one of the oldest known leaf vegetables consumed by humans. It is a member of the family Brassicaceae, botanically related to garden cress, mustard, radish, and wasabi—all noteworthy for their piquant flavor.
The hollow stems of watercress will float; the leaf structure is pinnately compound. Small, white and green flowers are produced in clusters and are frequently visited by insects, especially hoverflies such as Eristalis flies.7
Cultivation of watercress is practical on both a large-scale and a garden-scale. Being semi-aquatic, watercress is well-suited to hydroponic cultivation, thriving best in water that is slightly alkaline. It is frequently produced around the headwaters of chalk streams. In many local markets, the demand for hydroponically grown watercress exceeds supply, partly because cress leaves are unsuitable for distribution in dried form, and can only be stored fresh for a short period.
Watercress can be sold in supermarkets in sealed plastic bags, containing a little moisture and lightly pressurised to prevent crushing of contents. This has allowed national availability with a once-purchased storage life of one to two days in chilled or refrigerated storage. Also sold as sprouts, the edible shoots are harvested days after germination. If unharvested, watercress can grow to a height of 50 to 120 centimetres (1 1⁄2–4 ft). Like many plants in this family, the foliage of watercress becomes bitter when the plants begin producing flowers.7
Watercress crops grown in the presence of manure can be an environment for parasites such as the liver fluke, Fasciola hepatica. By inhibiting cytochrome P450 (CYP2E1), compounds in watercress may alter drug metabolism in individuals on certain medications such as "chlorzoxazo..".7