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Persicaria

Genus of flowering plants in the knotweed family

Wikipedia contributorsAdapted for Fathomly · View authors
4 min read
Source updated August 25, 2026
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Persicaria is a genus of herbaceous flowering plants in the knotweed family, Polygonaceae. Plants of the genus are known commonly as knotweeds or smartweeds. It has a cosmopolitan distribution, with species occurring nearly worldwide. The genus was segregated from Polygonum.

01Description

The genus includes annual and perennial herbs with taproots or fibrous root systems, or with rhizomes or stolons. The stems are often erect but may be prostrate along the ground, and some species are prickly. The stems are self-supporting or twining and climbing. The leaves are alternately arranged, deciduous, and variously shaped. The brownish or reddish ochrea may be leathery to papery. The inflorescence may be a panicle or a spikelike or headlike arrangement of fascicles of flowers. The flower is white, greenish, reddish, pink or purple, with the tepals partially fused together along the bases. The fruit is an achene which can take a number of shapes, including a disc or a sphere.

Illustration from the Japanese agricultural encyclopedia Seikei Zusetsu (1804)
Illustration from the Japanese agricultural encyclopedia Seikei Zusetsu (1804)

02Taxonomy

Within the family Polygonaceae, Persicaria is placed in the subfamily Polygonoideae, where the tribe Persicarieae consists of two sister genera, Bistorta and Koenigia, together with Persicaria.

Persicarieae

Persicaria

Bistorta

Koenigia

Species

As of November 2023, the following 132 species were accepted:

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Sources and credits

This article is adapted from the Wikipedia article “Persicaria”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

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