''Persicaria hydropiper'' (

syn. The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linnae ...

''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 1789 ...

. 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 geographical and ethno-cultural terms. The modern states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. China, North Korea, South Korea and ...

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 stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

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, and prefers damp environments for optimal growth; it will readily grow in riparian zones 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 flow un ...

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 ingredients. Two bicyclic sesquiterpenoids 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 with a

drimane Drimane is a bicyclic sesquiterpene. It is the parent structure of many natural products with various biological activity. Among the notable drimanes are: *Polygodial, found in several different plants *Multiple compounds found in several members ...

backbone), and warburganal, which gives it its pungent taste. The plant also contains rutin, a source of the bitter taste impression. Water pepper contains an

essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...

(0.5%) which consists of monoterpenoids and sesquiterpenoids: α-pinene, 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 Humulene, also known as α-humulene or α-caryophyllene, is a naturally occurring monocyclic sesquiterpene (C15H24), containing an 11-membered ring and consisting of 3 isoprene units containing three nonconjugated C=C double bonds, two of them be ...

β-caryophyllene Caryophyllene (), more formally (−)-β-caryophyllene, (BCP), is a natural bicyclic sesquiterpene that is a constituent of many essential oils, especially clove oil, the oil from the stems and flowers of ''Syzygium aromaticum'' (cloves), the esse ...

trans-β-bergamotene Bergamotenes are a group of isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is exi ...

Carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...

s ( cinnamic, valeric and caproic acid) 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 ar ...

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 Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

, where it is known as ''tade'' (蓼), or more specifically, ''yanagi tade'' (柳蓼). The

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

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 which has a far more pungent 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, stuck) ...

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 ''tem ...

, and sushi. It is popular for summer cooking. The seeds may also be added to wasabi. 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 et ...

, and a small amount of steamed rice. 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 other ...

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 s ...

, 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 action ...

. 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 Formic acid (), systematically named methanoic acid, is the simplest carboxylic acid, and has the chemical formula HCOOH and structure . It is an important intermediate in chemical synthesis and occurs naturally, most notably in some ants. Es ...

, 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' ''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