Knotweed. Bistort, Smart Weed

Annuals and perennials with an erect or decumbent growth habit, or occasionally rhizomatous. The leaf under-surface is commonly a lighter colour than the top. Flowers have 4 or 5 petals and are commonly pink or white, but occasionally greenish.


Ornamental plants.  Foliage of some species can cause an allergic reaction on the skin of animals and people. They may become invasive weeds.


They grow best in full sun or semi-shade in moist or wet soils, but well-drained soil is preferred. They will tolerate a wide range of soil pH and texture conditions.


They are easy to propagate by division in spring or autumn.


Around 150 species. Cultivated species include:
P. bistorta (syn. Bistorta officinalis: Snakeweed) - to 1m tall x 60cm spread with pale green leaves and spikes of pink flowers.
P. major
P. odorata
P. virginiana.

Plant Health

These plants are generally free of serious pest or disease problems.

More info

syn. Bistorta, Aconogonon

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