Characterisistics of water pepper

What is water pepper (Polygonum hydropiper) ?

Characteristics of water pepper

Common English name: water-pepper, water pepper, common smartweed.

Scientific name: Polygonum hydropiper

Taxonomic Synonyms:

– Gray acris Persicaria nom. illeg.

– Persicaria flaccida (Meisn.) H.Gross

– Hydropiper persicaria (L.) Spach

– Hydropiper persicaria (L.) Delarbre

Family: Polygonaceae

Habitat: Native Plant of the European continent, distributed in cold and temperate regions. It is located on the Eurasian continent (Caucasus, Siberia) and North America (Mexico, USA, Canada).

It likes high humidity and high nitrogen soils, growing naturally in swamps, rivers,, etc.. It does not tolerate calcareous soils.

Botanical description of water pepper

The smartweed (Polygonum hydropiper) is an annual herb, 20 to 60 cm tall, usually branched and hairless.

Stems erect, greenish or reddish. Its small petiolated leaves (1) are alternate, lanceolate, acute, entire margins, about 2 cm wide and 12 cm long. They are covered with transparent essence glands.

At the base of each leaf there are the ochreas (2), which are membranous structures departing from the corners of the leaves that surround the stem like a sheath.

In botany, the nodal ocreas typical structures of the Polygonaceae family.

The inflorescences are terminal hanging racemes (3), between 1 and 6 per plant, where the flowers are arranged.

Pepper aquatic blooms in summer and autumn. The flowers are small, about 4 mm long, whitish or greenish, stained with red at maturity. It is a honey plant.

The fruit is an lenticular (compressed) trigonal (triangular) achene or, as if the flower contained two or three styles. It is brown, approximately 3 millimeters.

This fruit has a strong spicy flavor similar to the taste of chilli.

pimienta agua

In the picture: botanical illustration of smartweed, showing the stems, leaves and terminal inflorescences of the plant.

Composition of water pepper

Essential oil: 1,4-cineole, alpha-pinene, beta-pinene, borneol, camphor, carvone, cinnamic acid, cinnamic alcohol, fenchone, P-cymol, phellandrene, poligonone, terpineol.

Organic acids: formic acid, acetic acid, valeric acid, gallic acid, malic acid, melissic acid, ellagic acid, baldrianic acid, caprionic acid. tannic acid.

Anthraquinones:oxy methyl anthraquinone (root). Purging compound also present in other Polygonaceae such as rhubarb.


Phytosterols: beta-sitosterol, sitosterol

Sesquiterpenes: polygodial (leaves), polygonal (seeds), confertiflorin (seeds), isodrimeninol (seed), isopolygodial (seed), isorhamnetin, isodrimenol, isotadeonal, polygonolide.


Flavonoids: rutin, kaempferol, quercetin, quercitrin, rhamnazin, rhamnesin.

Salts: potassium nitrate, potassium chloride.

Water piper composition

(Polygonum hydropiper)


(en ppm.)

Rutin (leaves)25.000 – 30.000
Potassium chloride26.000

punto rojo More information about water pepper and other types of peppers

Botanical classification

Vascular plants


Seed plants


Flower plants



SpeciesP. hydropiper

punto rojo More information about water pepper and other types of peppers

This article was endorsed by Montserrat Enrich - Journalist specializing in edible wild plants and plant uses.
Written by Editorial Botanical-online team in charge of content writing

3 November, 2022

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