Information on Lesser Knotweed

Common Name: Lesser Knotweed
Scientific Name: Persicaria campanulata
Irish Name: Glúineach an chlúimh
Family Group: Polygonaceae
Distribution: View Map (Courtesy of the BSBI)
Flowering Period


Click for list of all flowering by month
Lesser Knotweed could sometimes be confused with:

Knotweed, Himalayan, Knotweed, Japanese,

With graceful reddish branches bearing panicles of little creamy-pink flowers (5-7mm each), this perennial shrub grows in shady places and on occasional damp roadsides. It can reach over 1 metre high and displays its pretty flowers from July to early September.  Also branching from the stems are distinctive oval, pointed leaves which have clearly marked herring-bone pattern ridges, more conspicuous when viewed from the underside of the leaf which is also markedly felted and a light green or buff colour.  An introduced plant, it belongs to the Polygonaceae family.  

I first recorded and also photographed this shrub near Corr na Móna, Co Galway in 2009.  

If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre

Knotweed, Lesser
Knotweed, Lesser

This plant, which comes from the Himalayas, has found a home in only a few wild places in Ireland.  Originally planted as an ornamental shrub, its status in Ireland is now that of 'naturalised' and 'potentially invasive'.