Information on Pink Knotweed

Common Name: Pink Knotweed
Scientific Name: Persicaria capitata
Irish Name: Not known at present
Family Group: Polygonaceae
Distribution: View Map (Courtesy of the BSBI)
Flowering Period


Click for list of all flowering by month
Pink Knotweed is not easily confused with other wild plants on this web site.


Originally from the Himalayas, this little plant is a recent introduction into Ireland. It is an extremely pretty little sprawling, creeping, glandular-hairy perennial plant with round, dense, terminal heads of tiny, pale-pink, 5-tepalled flowers (1mm) on branching brownish-red stems which only grow to about 50cm. The distinctive leaves are ovate-elliptic with central red stems and they each have a dark-red or brown chevron across the centre. The veins are also red and plainly marked. It is clearly not a native plant and is a member of the Polygonaceae or Knotweed family. It flowers from May to August.

I first saw this plant growing along pavements and gutters in Newport, Co Mayo in July 2014 when I also photographed it. I think it may have escaped from window-boxes and was doing extremely well in spreading itself. 

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

Knotweed, Pink
Knotweed, Pink

Also known as Pink-headed Persicaria, this garden escape is not thought to be totally frost-hardy and therefore may not overwinter.However, it is known to be a species which grows vigorously and with little or no maintainance it can survive and get out of hand all too quickly, given the right conditions. It would be a shame if it were to be a future ‘invasive species’.