Water Knotweed, Willow grass, Amphibious bistort
Persicaria amphibia

Family: Polygonaceae

What it is like

A herb which keeps growing from year to year. The stems trail from the base and root at the nodes. In water the stems are hollow which can be 1 m long. The leaves are sword shape and emerge from the water. They clasp the stem. The leaves are more round when floating. The long leaf stalks emerge from a papery sheath. The leaves are dark green and glossy. They taper to a blunt tip and have dark markings near the tip. The flowers are in neat pink spikes.

There are about 50 Polygonum species.

Where it is found

It is a temperate plant. It can grow in or near water. It suits slow moving water.

Countries/locations it is found in

Asia, Britain, Canada, Central Asia, East Africa, Eritrea, Europe, Korea, Luxembourg, North America, Spain, Tajikistan, Turkey, Türkiye, USA

How it is used for food

The fruit are used as a substitute for pepper. The leaves are cooked as a vegetable dish.

Edible parts

Leaves, seeds

How it is grown

Its other names

Local names

Istir, Kizilbacak, Kune

Synonyms

Chulusium amphibium (L.) Raf.; Chulusium fluitans Raf.; Chulusium natans Raf.; Persicaria amphibia (L.) Gray; Persicaria amurensis (Korsh.) Nieuwl.; Persicaria coccinea (Muhl.) Greene; Persicaria hartwrightii (A. Gray) Greene; Persicaria muhlenbergii (Meisn.) Small; Polygonium amphibium L.; Polygonum amurense Nieuwl.; Polygonum coccineum Muhl.; Polygonum emersum (Michx.) Britton; Polygonum hartwrightii A. Gray; Polygonum muhlenbergii (Meisn.) S. Watson;