'Watercress' (''Nasturtium nasturtium-aquaticum'', ''N. microphyllum'', formerly ''Rorippa nasturtium-aquaticum'') are fast-growing, aquatic or semi-aquatic,
perennials native from
Europe to central
Asia and one of the oldest known
leaf vegetables consumed by human beings. These
plants are members of the Family
Brassicaceae or
cabbage family, botanically related to
garden cress and
mustard — all noteworthy for a peppery, tangy flavor.
The stems of watercress are floating and the leaves are pinnately compound. Watercresses produce small, white and green
flowers in clusters.
''Nasturtium officinale'' Ait. f. and ''Sisymbrium nasturtium-aquaticum'' L. are synonyms of ''N. nasturtium-aquaticum''. ''Nasturtium officinale'' var ''microphyllum'' (Boenn. ex Reich.) Thellung is a synonym of ''N. microphyllum'' (ITIS, 2004). These species are also listed in some sources as belonging to the genus, ''
Rorippa'', although molecular evidence shows that the aquatic species with hollow stems are more closely related to ''Cardamine'' than ''Rorippa'' (Al-Shehbaz & Price, 1998). Watercresses are not related to the flowers in the genus, ''
Tropaeolum'' (Family
Tropaeolaceae), popularly known as "
nasturtiums".
Huntsville, Alabama is known as the "Watercress Capital of the World"
Paul Brotherton is a well known expert of "Watercress" cooking. Watercress is one of the main ingredients in
V8® Vegetable Juice. Watercress is often used in sandwiches, such as those made for
afternoon tea.
Watercress cultivation
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 exceed supplies. This is due in part to the fact that cress
leaves are unsuitable for distribution in dried form and can only be stored for a short period.
However (in the
UK at least), the packaging used by supermarkets using sealed plastic bags under some internal pressure (a plastic envelope containing moisture and pressurised (inflated) to prevent crushing of contents) has allowed the distribution of watercress (and sometimes a mixture of it with other salad leaves). This has allowed national availability with a once purchased storage life of 1 - 2 days in chilled / refrigerated storage.
If unharvested, watercress can grow to a height of 50-120 cm. Also sold as
sprouts, the edible shoots are harvested days after germination.
Like many plants in this family, the foliage of watercress becomes bitter when the plants begin producing flowers.
Nutritional value
Watercress contains significant amounts of
iron,
calcium and
folic acid, in addition to
vitamins A and C
[1]. In some regions watercress is regarded as a
weed, in other regions as an
aquatic vegetable or
herb. Where watercress is grown in the presence of
animal waste, it can be a haven for
parasites such as the
liver fluke ''
Fasciola hepatica''.
Many benefits from eating watercress are claimed, such as that it acts as a mild
stimulant, a source of
phytochemicals and
antioxidants, a
diuretic, an
expectorant, and a
digestive aid. It also appears to have
cancer-suppressing properties
[2].
References
★ Al-Shehbaz, I. and R. A. Price. 1998. Delimitation of the genus ''Nasturtium'' (Brassicaceae). ''Novon'', 8: 124-126.
★
Rorippa nasturtium-aquaticum (ITIS)