Watercress, Onerow yellowcress
Nasturtium microphyllum
Family: Brassicaceae or Cruciferae
What it is like
Nasturtium microphyllum is a PERENNIAL growing to 0.5 m (1ft 8in) by 1 m (3ft 3in). See above for USDA hardiness. It is hardy to UK zone 6 and is not frost tender. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees, flies. The plant is self-fertile. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers wet soil and can grow in water.
Height (m): 0.5
Where it is found
Stream margins, ditches, flushes etc with moving water, usually in chalk or limestone areas.
Europe, including Britain, to W. Asia.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 3
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.
Seed: includes nuts, cereals, peas and beans.
Condiment: the various plants that are used as flavourings, either as herbs, spices or condiments.
Medicine
Rating: 1
Antiscorbutic, diuretic, expectorant, purgative, stimulant, stomachic. Use with caution.
Antiscorbutic: A plant rich in vitamin C that is used to counteract scurvy.
Diuretic: Acts on the kidneys, promoting the flow of urine.
Expectorant: Clears phlegm from the chest by inducing coughing.
Purgative: A drastic laxative causing a cleansing or watery evacuation of the bowels, usually with a griping pain.
Stimulant: Excites or quickens activity of the physiological processes. Faster acting than a tonic but differing from a narcotic in that it does not give a false sense of well-being.
Stomachic: Aids and improves the action of the stomach.
Other
Rating: 0
How it is grown
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.
Propagating it: 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.
Best place to grow: Pond; Bog Garden;
Habit: Perennial
Hardiness: 5-9
Growth:
Soil: Light (sandy), medium, heavy (clay)
Shade: No shade
Moisture: Wet, water