Watercress or yellowcress (Nasturtium officinale) is a species of aquatic flowering plant in the cabbage family, Brassicaceae.

Small, white,[3] and green inflorescences are produced in clusters and are frequently visited by insects, especially hoverflies, such as Eristalis flies.

[10] Many settlements in England are named after watercress, from Old English êacerse, including Kersey, Kesgrave, Kersal, and Kershopefoot.

With the introduction of watercress, the organic matter in the sediment increases which in turn attracts predatory macroinvertebrates that feed on other plants in the environment.

[17] In China watercress is often boiled alongside pork and traditional medicinal ingredients to make a wintertime tonic soup.

[18] Twelfth-century mystic Hildegard of Bingen thought eating it steamed and drinking the water would cure jaundice or fever.

As a cruciferous vegetable, watercress contains isothiocyanates that are partly destroyed by boiling, while the bioavailability of its carotenoids is slightly increased by cooking.

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 about 2–3 days.

Historically important areas of cultivation also included Hampshire, Stamford, and Watercress Wildlife Site at St Albans.