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Common Name: Watercress

General Information

Nasturtium microphyllum is a perennial plant that can grow up to 0.50 metres tall.
It is harvested from the wild for local use as a food and medicine

Known Hazards

None known

Botanical References

Range

Europe, including Britain, to W. Asia.

Habitat

Stream margins, ditches, flushes etc with moving water[, ], usually in chalk or limestone areas[].

Properties

Edibility Rating
Medicinal Rating
Habit	Perennial
Height	0.50 m
Pollinators	Bees, Flies, Self
Self-fertile	Yes
Cultivation Status	Wild

Cultivation Details

Watercress is easily grown when given the correct conditions of slowly flowing clean water, preferably coming from chalky or limestone soils[]. It prefers to grow in water about 5cm deep[] with an optimum pH 7.2[]. Plants can be grown in wet soil if the position is somewhat shaded and protection is given in winter, though the flavour may be hotter[, ].
Plants are hardy to about -15°c[], they tolerate somewhat lower temperatures than the closely related N. officinale[].
Watercress is often cultivated for its edible leaves, there are some named varieties[, ]. The plant is very sensitive to pollution so a clean source of water is required[]. Plants will often continue to grow all through mild winters. A fast-growing plant, the stems trail along the ground or float in water and produce new roots at the leaf nodes, thus making the plant very easy to propagate vegetatively[]. Unfortunately, virus diseases have become more common in cultivated plants and so most propagation is carried out by seed[].
This is a triploid species. It has hybridised naturally in the wild with the diploid species N. officinale to produce the sterile hybrid N. x sterilis which is also commonly cultivated as a salad crop[].
The flowers are a rich source of pollen and so are very attractive to bees[].

Edible Uses

Leaves - raw or cooked[, , , , , ]. Exceptionally rich in vitamins and minerals, especially iron[]. The leaves are mainly used as a garnish or as an addition to salads, the flavour is strong with a characteristic hotness[].
The seed can be sprouted and eaten in salads[]. A hot flavour.
The seed is ground into a powder and used as a mustard[, ]. The pungency of mustard develops when cold water is added to the ground-up seed - an enzyme (myrosin) acts on a glycoside (sinigrin) to produce a sulphur compound. The reaction takes 10 - 15 minutes. Mixing with hot water or vinegar, or adding salt, inhibits the enzyme and produces a mild but bitter mustard[].

Medicinal

Antiscorbutic, diuretic, expectorant, purgative, stimulant, stomachic[, , , ]. Use with caution[].

Other Uses

None known

Propagation

Seed - sow spring in a pot emmersed to half its depth in water. Germination should take place within a couple of weeks. Prick out seedlings into individual pots whilst they are still small and increase the depth of water gradually until they are submerged. Plant out into a pond in the summer.
Cuttings can be taken at any time in the growing season. Virtually any part of the plant, including a single leaf, will form roots if detached from the parent plant[]. Just put it in a container of water until the roots are well formed and then plant out in shallow water.