''Persicaria hydropiper'' ( syn. ''Polygonum hydropiper''), also known as water pepper, marshpepper knotweed, arse smart or tade, is a plant of the family

Polygonaceae The Polygonaceae are a family of flowering plants known informally as the knotweed family or smartweed—buckwheat family in the United States. The name is based on the genus '' Polygonum'', and was first used by Antoine Laurent de Jussieu in 1 ...

. A widespread species, ''Persicaria hydropiper'' is found in Australia, New Zealand, temperate Asia, Europe and North America. The plant grows in damp places and shallow water. Cultivated varieties are eaten in

East Asia East Asia is the eastern region of Asia, which is defined in both Geography, geographical and culture, ethno-cultural terms. The modern State (polity), states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. ...

for their pungent flavor.

Description

Water pepper is an annual herb with an erect stem growing to a height of . The leaves are alternate and almost stalkless. The leaf blades are narrowly ovate and have entire margins fringed by very short hairs. They are tapering with a blunt apex. Each leaf base has stipules which are fused into a stem-enclosing sheath that is loose and fringed at the upper end. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...

is a nodding spike. The perianth of each tiny flower consists of four or five segments, united near its green base and white or pink at the edges. There are six stamens, three fused carpels and three styles. The fruit is a dark brown oval, flattened nut. ''P. hydropiper'' is an

annual Annual may refer to: *Annual publication, periodical publications appearing regularly once per year ** Yearbook ** Literary annual *Annual plant *Annual report *Annual giving *Annual, Morocco, a settlement in northeastern Morocco *Annuals (band), ...

, and prefers damp environments for optimal growth; it will readily grow in

riparian zone A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks a ...

s on the banks of streams and rivers, but can also grow in other areas where water collects, such as on the banks of

canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface flo ...

s, tyre and hoof tracks in woodlands, waterlogged soil, and around gates in fields. ''P. hydropiper'' is also tolerant of partial shade and base-poor soil. In the United Kingdom, where the plant is native, it can grow at any altitude between sea level and 505 metres.

Biochemistry

Water pepper has several

active ingredient An active ingredient is any ingredient that provides biologically active or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease or to affect the structure or any function of the body of humans or animals. The ...

s. Two bicyclic

sesquiterpenoid Sesquiterpenes are a class of terpenes that consist of three isoprene units and often have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be cyclic or contain rings, including many unique combinations. Biochemical modificatio ...

s are present,

polygodial Polygodial is chemical compound found in dorrigo pepper, mountain pepper, horopito, canelo, paracress, water-pepper, and '' Dendrodoris limbata''.M Jonassohn (1996)Sesquiterpenoid unsaturated dialdehydes - Structural properties that affect r ...

(tadeonal, an unsaturated

dialdehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group ...

with a drimane backbone), and warburganal, which gives it its pungent taste. The plant also contains

rutin Rutin, also called rutoside, quercetin-3-O-rutinoside and sophorin, is the glycoside combining the flavonol quercetin and the disaccharide rutinose (α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranose). It is a flavonoid found in a wide variety of pl ...

, a source of the bitter taste impression. Water pepper contains an essential oil (0.5%) which consists of

monoterpenoid Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen funct ...

s and

α-pinene α-Pinene is an organic compound of the terpene class, one of two isomers of pinene. It is an alkene and it contains a reactive four-membered ring. It is found in the oils of many species of many coniferous trees, notably the pine. It is also ...

, β-pinene, 1,4-cineol,

fenchone Fenchone is an organic compound classified as a monoterpenoid and a ketone. It is a colorless oily liquid. It has a structure and an odor similar to those of camphor. Fenchone is a constituent of absinthe and the essential oil of fennel. Fen ...

, α-humulene, β-caryophyllene, trans-β-bergamotene. Carboxylic acids ( cinnamic, valeric and

caproic acid Caproic acid, also known as hexanoic acid, is the carboxylic acid derived from hexane with the chemical formula . It is a colorless oily liquid with an odor that is fatty, cheesy, waxy, and like that of goats or other barnyard animals. It is a f ...

) and their

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides a ...

s were present in traces. The composition depends strongly on genetic factors. Wild water pepper produces oils that cause skin irritation.

Uses

Water pepper is eaten in Japan, where it is known as ''tade'' (蓼), or more specifically, ''yanagi tade'' (柳蓼). The leaves are used as a

vegetable Vegetables are parts of plants that are consumed by humans or other animals as food. The original meaning is still commonly used and is applied to plants collectively to refer to all edible plant matter, including the flowers, fruits, stems, ...

, but only from the

cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...

, not the

wild type The wild type (WT) is the phenotype of the typical form of a species as it occurs in nature. Originally, the wild type was conceptualized as a product of the standard "normal" allele at a locus, in contrast to that produced by a non-standard, "m ...

which has a far more

pungent Pungency () refers to the taste of food commonly referred to as spiciness, hotness or heat, found in foods such as chili peppers. Highly pungent tastes may be experienced as unpleasant. The term piquancy () is sometimes applied to foods with a l ...

taste. The herb is usually sold in markets as seedlings. Young red sprouts are known as ''beni-tade'' (紅蓼), and are used to garnish

sashimi is a Japanese delicacy consisting of fresh raw fish or meat sliced into thin pieces and often eaten with soy sauce. Origin The word ''sashimi'' means "pierced body", i.e. " 刺身" = ''sashimi'', where 刺し = ''sashi'' (pierced, stu ...

tempura is a typical Japanese dish usually consisting of seafood, meat and vegetables that have been battered and deep fried. The dish was introduced by the Portuguese in Nagasaki through fritter-cooking techniques in the 16th century. The word ...

, and

sushi is a Japanese dish of prepared , usually with some sugar and salt, accompanied by a variety of , such as seafood, often raw, and vegetables. Styles of sushi and its presentation vary widely, but the one key ingredient is "sushi rice," also ...

. It is popular for summer cooking. The seeds may also be added to

wasabi Wasabi ( Japanese: , , or , ; ''Eutrema japonicum'' or ''Wasabia japonica'') or Japanese horseradish is a plant of the family Brassicaceae, which also includes horseradish and mustard in other genera. The plant is native to Japan and the Russi ...

. Water pepper sauce, known as ''tade-zu'' (蓼酢), is a sauce traditionally made from finely chopped water pepper leaves, soaked in

vinegar Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. Vinegar typically contains 5–8% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting simple sugars to eth ...

, and a small amount of

steamed rice Cooked rice refers to rice that has been cooked either by steaming or boiling. The terms steamed rice or boiled rice are also commonly used. Any variant of Asian rice (both Indica and Japonica varieties), African rice or wild rice, glutinous ...

. Occasionally, the juice from a squeezed

kabosu Kabosu (カボス or 臭橙; binomial name: ''Citrus sphaerocarpa'') is a citrus fruit of an evergreen broad-leaf tree in the family Rutaceae. It is popular in Japan, where its juice is used to improve the taste of many dishes, especially cooke ...

is added. In

Japanese cuisine Japanese cuisine encompasses the regional and traditional foods of Japan, which have developed through centuries of political, economic, and social changes. The traditional cuisine of Japan (Japanese: ) is based on rice with miso soup and oth ...

it is traditionally used as a complement to

grilled Grilling is a form of cooking that involves dry heat applied to the surface of food, commonly from above, below or from the side. Grilling usually involves a significant amount of direct, radiant heat, and tends to be used for cooking meat a ...

freshwater fish Freshwater fish are those that spend some or all of their lives in fresh water, such as rivers and lakes, with a salinity of less than 1.05%. These environments differ from marine conditions in many ways, especially the difference in levels of ...

, but not saltwater fish. In China, water pepper is known as ''la liao'' (辣蓼), and used in

traditional Chinese medicine Traditional Chinese medicine (TCM) is an alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logical mechanism of acti ...

. In Europe, water pepper was once cultivated and eaten during war time as a substitute for pepper. The plant contains many acids, including formic acid, which makes it unpalatable to livestock.Illinois Wildflowers
/ref> Though mammals do not eat wild water pepper, some insects do, giving rise to the Japanese saying "''Tade kuu mushi mo sukizuki''" (蓼食う虫も好き好き "Some insects eat water pepper and like it"), which may be translated as “There is no accounting for taste” or “Some prefer nettles.”

Gallery

Polygonum hydropiper1.jpg Persicaria hydropiper.JPG Polygonum hydropiper3.jpg Polygonum hydropiper2.jpg Polygonum hydropiper — Flora Batava — Volume v6.jpg, Illustration from

Jan Kops Jan Kops (6 March 1765 Amsterdam - 9 January 1849 Utrecht) was an Anabaptist Dutch agronomist and botanist. His most notable contribution to botany was the founding of the long-lived journal "''Flora Batava''" in 1800 and contributing text for th ...

' ''Flora Batava'' (1832) Polygonum hydropiper (1832).jpg, Illustration from ''La flore et la pomone françaises'' (1832) 356 Polygonum tomentosum, Polygonum hydropiper.jpg, Illustration from ''Bilder ur Nordens Flora'' (1917-1926)

References

External links

Jepson Manual Treatment, University of California

Australian Plant Name Index (APNI)
{{Taxonbar, from=Q160113 hydropiper Spices Flora of Europe Flora of Australia Flora of Asia Flora of North America Plants described in 1753 Taxa named by Carl Linnaeus