Nasturtium is a small genus of aquatic and semi-aquatic flowering plants in the family Brassicaceae (the cabbage family), within the order Brassicales. Commonly known as watercress or yellowcress, the genus comprises a handful of species native primarily to Europe, western Asia, and parts of North America, though watercress is now naturalised and cultivated worldwide.
The genus is best known for Nasturtium officinale (common watercress), a fast-growing, semi-aquatic herb long prized as an edible green. Its leaves and stems have a distinctively peppery, tangy flavour, shared across the genus — a characteristic that connects it botanically to relatives such as garden cress and mustard. The genus name itself alludes to this quality: Nasturtium derives from the Latin nasus tortus, meaning "twisted nose," a reference to the sensory effect of eating these pungent plants.
Taxonomically, Nasturtium has historically been a point of debate. It was at one point synonymised with the broader genus Rorippa, but molecular phylogenetic evidence has since confirmed it as a distinct lineage, more closely allied to Cardamine than to Rorippa sensu stricto. Plants of the World Online currently recognises a small number of accepted species and one hybrid (N. × sterile, the cross between N. officinale and N. microphyllum). Several names sometimes placed in Nasturtium — including Nasturtium africanum — are now treated as synonyms of Rorippa species.
Beyond their culinary use, Nasturtium plants serve as larval food plants for certain Lepidoptera, including the moth Orthonama obstipata (The Gem). One species, Nasturtium gambellii (Gambel's watercress), is federally listed as endangered in California due to its restricted range and habitat loss.
Etymology
The name Nasturtium is derived from the Latin nasus tortus, meaning "twisted nose." This vivid name refers to the pungent, peppery sensation that eating these plants produces in the nasal passages — a quality shared across the genus and its close relatives in the mustard family.
Distribution
The genus is native to Europe, western Asia, and parts of North America, typically growing in or near flowing freshwater streams, ditches, and springs. Nasturtium officinale is now widely naturalised and cultivated across temperate and subtropical regions worldwide. Nasturtium gambellii has an exceptionally restricted native range in California and is federally listed as an endangered species.
Taxonomy Notes
Nasturtium was historically synonymised with the genus Rorippa, but molecular phylogenetic evidence has re-established it as a distinct genus within Brassicaceae. It is now considered more closely related to Cardamine than to Rorippa sensu stricto. Plants of the World Online currently accepts five taxa: N. floridanum, N. gambellii, N. microphyllum, N. officinale, and the hybrid N. × sterile. Several names previously placed in Nasturtium, including Nasturtium africanum, are treated as synonyms of Rorippa.
Cultural Uses
Watercress (Nasturtium officinale) is one of the oldest known leaf vegetables consumed by humans, eaten raw in salads, as a garnish, and in soups. Its peppery flavour and high nutrient content — including vitamins C and K, calcium, and iron — have made it a staple in European and Middle Eastern cuisines for centuries. The plant has also been used in traditional medicine across several cultures, attributed with diuretic and stimulant properties.
