Water Smartweed – Persicaria Amphibia: Edible & Medicinal Uses of the Water Buckwheat of Wild Plants

Table of Contents

Water smartweed (persicaria amphibia syn. polygonum amphibium) is another edible and medicinal plant from the buckwheat family. It is native to Ontario and has the showiest flower of all our local smartweeds.

Water smartweed (persicaria amphibia syn. polygonum amphibium) since the compilation of Haliburton Flora got a new genus, persicaria. It’s common here in wet ditches, shoresides and banks, and in quiet waters up to 1 m deep. This smartweed has an aquatic form and a terrestrial form. The bright pink flowers stand out in the summer and lucky for us it’s native. Another wet-loving native smartweed is dotted (persicaria punctata syn. polygonum punctatum), but it has white flowers. There are at least 22 species of persicaria sighted in Ontario.

Lady’s thumb is a related plant we’ve already covered, a nonnative with less local wildlife consuming it, so it’s the most sighted wild buckwheat on iNat for Ontario. But our pretty water smartweed comes in second for sightings.

Water smartweed (Persicaria amphibia syn. Polygonum amphibium)
Water smartweed (Persicaria amphibia syn. Polygonum amphibium)

Edible Uses of Water Smartweed

All the smartweeds are edible. The peppery leaves can be eaten raw or cooked. And the young shoots can be eaten in the spring.

The smartweeds are related to buckwheat and the nutty seeds are small but edible raw or cooked.

Note that water smartweed absorbs toxic metals, so don’t forage from polluted waters. Some waters around here look clean, but have tailings from mining.

P. a. var. stipulacea aquatic form

Medicinal Uses of Water Smartweed

Water Smartweed is primarily said to support these body systems:

  • Digestive

Medicinal tags include Astringent. See Medicinal tag key for more information.

Common usage includes an infusion of the leaves and stems for stomach pains and other typical astringent plant uses. The root can be sucked on to treat a sore throat.

Another smartweed that gets called water smartweed is p. punctatum, AKA “water pepper”. I had some of this spontaneously show up in a wet planter at the one acre. It’s used similarly and looks somewhat like a tiny version of our title plant. Or like a lady’s thumb without the thumbprint.

Water smartweed (Persicaria amphibia syn. Polygonum amphibium)

Alternative Uses of Water Knotweed

The dried flower may attract white-tailed deer when smoked.

Its ability to absorb metals makes it a contender for cleaning up toxic waters.

Growing Persicaria Amphibia

P. Amphibia has the showiest flower of native smartweeds in Ontario. It’s a wonderful plant to include in quiet waters on your property. In parts of the world where water smartweed is not native it is aggressively taking over wetlands. Introducing nonnative species to any area can cause serious damage, because if a plant didn’t adapt and evolve with the local species it can just grow unchecked, eliminating the biodiversity that is necessary for a healthy ecosystem.

You can sow or root this plant during springtime in a cold frame, transferring the seedlings into their own pots for tending. Plant them in the summer. Or just divide in spring or autumn. You may want to tend smaller divisions before planting too.

Many insects will feed on these including pollinators and the caterpillars of two Ontario butterflies, purplish copper (lycaena helloides), and more likely to be seen around Haliburton, the bronze copper (lycaena hyllus). The seedheads are eaten by many birds, turtles and even muskrats will dine on smartweed sometimes.


Accumulates toxic metals from polluted water.

May cause photosensitivity in susceptible people.

And the Usual Cautions:

1) Most medicinal herbs, if edible, are meant to be eaten in moderation, even sparingly. Some require extra preparation. Tannins are toxic if consumed in excess.

2) People can be allergic or sensitive to nearly any plant; try new herbs one at a time at your own risk. For instance, saponins commonly cause stomach upset.

3) For medicinal use, I must recommend receiving a diagnosis and working with a reputed health care provider. I generally do not post specific treatments and dosages because I think that is best between you and your health care provider, and ideally monitored.

4) Anyone pregnant, nursing, or taking prescription drugs should talk to a health care professional before adding new food items to their diet.

5) Many plants have look-a-likes, and sometimes they are poisonous.

#ads in References

As an Amazon Associate I earn from qualifying purchases. Every book I reference that is available on Amazon is linked to with an associates link.



Field Guide to Medicinal Wild Plants

Medicinal and Other Uses of North American Plants: A Historical Survey with Special Reference to the Eastern Indian Tribes

Edible and Medicinal Plants of Canada

Please Like, Comment, Share! We'd love to hear your stories and knowledge! Thank you!

Leave a Comment