Flora of Northern Ireland
  • Persicaria wallichii Greuter & Burdet - Himalayan Knotweed - Polygonaceae
Persicaria wallichii
© Graham Day
Persicaria wallichii
© Paul Hackney
Persicaria wallichii
© Graham Day
Persicaria wallichii
(Map updated: March 2008)
 

One of several foreign knotweeds introduced for garden purposes in the nineteenth century from the Himalayas and now established in a few places in the wild - on roadsides, maritime slopes etc. These wild colonies are the product of discarded garden rubbish containing bits of rhizome.

The leafy shoots grow up to about 6 feet high from underground rhizomes and produce clumps of small white or pale pink flowers in late summer.

Also called Polygonum polystachyum.

All names: Persicaria wallichii Greuter & Burdet; Persicaria polystachya (Wallich ex Meissner) Gross non Opiz; Polygonum polystachyum Wallich ex Meissner; Reynoutria polystachyum Wall. ex Meissner