View source for Watercress

{{Taxobox
| color = lightgreen
| name = Watercress
| image = Nasturtium_lvs.jpg
| image_width = 250px
| image_caption = ''Nasturtium microphyllum'', a watercress
| regnum = [[Plant]]ae
| phylum = [[Flowering plant|Magnoliophyta]]
| classis = [[Dicotyledon|Magnoliopsida]]
| ordo = [[Brassicales]]
| familia = [[Brassicaceae]]
| genus = ''[[Nasturtium (scientific name)|Nasturtium]]''
| subdivision_ranks = [[Species]]
| subdivision = 
''Nasturtium nasturtium-aquaticum'' L.<br>
''Nasturtium microphyllum'' Boenn ex Rchb.
}}
'''Watercress''' (''Nasturtium nasturtium-aquaticum'', ''N. microphyllum'', formerly ''Rorippa nasturtium-aquaticum'') are fast-growing, aquatic or semi-aquatic, [[Perennial plant|perennials]] native from [[Europe]] to central [[Asia]] and one of the oldest known [[leaf vegetable]]s consumed by human beings. These [[plant]]s are members of the Family [[Brassicaceae]] or  [[cabbage]] family, botanically related to [[garden cress]] and [[Mustard plant|mustard]] &mdash; 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 [[flower]]s 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 "[[Nasturtium (popular name)|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 (beverage)| V8®  Vegetable Juice]]. Watercress is often used in sandwiches, such as those made for [[Tea (meal)|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 [[hydroponics|hydroponic]] cultivation, thriving best in water that is slightly [[alkaline]]. It is frequently produced around the headwaters of [[chalk stream]]s. In many local markets the demand for hydroponically-grown watercress exceed supplies. This is due in part to the fact that cress [[Leaf|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 [[Sprouting|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 [[vitamin]]s A and C[http://www.lse.co.uk/ShowStory.asp?story=GE1534106Y&news_headline=watercress_diet_can_cut_the_risk_of_cancer]. In some regions watercress is regarded as a [[weed]], in other regions as an [[aquatic plant|aquatic]] [[vegetable]] or [[herb]]. Where watercress is grown in the presence of [[animal]] [[waste]], it can be a haven for [[parasite]]s such as the [[Liver Fluke|liver fluke]] ''[[Fasciola hepatica]]''{{Fact|date=February 2007}}.

Many benefits from eating watercress are claimed, such as that it acts as a mild [[stimulant]], a source of [[phytochemical]]s and [[antioxidant]]s, a [[diuretic]], an [[expectorant]], and a [[digestive]] aid{{Fact|date=February 2007}}. It also appears to have [[cancer]]-suppressing properties[http://www.lse.co.uk/ShowStory.asp?story=GE1534106Y&news_headline=watercress_diet_can_cut_the_risk_of_cancer].

==References==
* Al-Shehbaz, I. and R. A. Price. 1998. Delimitation of the genus ''Nasturtium'' (Brassicaceae). ''Novon'', 8: 124-126.   
* [http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=22993 Rorippa nasturtium-aquaticum] (ITIS)

[[Category:Herbs]]
[[Category:Aquatic plants]]
[[Category:Brassicaceae]]
[[Category:Leaf vegetables]]