Japanese knotweed Reynoutria japonica

Description

Japanese knotweed is a fast-growing perennial herb in the family Polygonaceae. It forms dense stands which may reach up to 3 m tall. In its native habitat in Japan, it usually grows only 0,3 to 1,5 m in height.

Japanese knotweed thrives in a wide range of habitats. It requires light to grow and, therefore, it favors sunny habitats such as riversides, landfills and along roads and railways. It also grows in semi-shaded places such as forest clearings and edges, but rarely in forest. It also thrives on clayey and very barren habitats, and it is not demanding on soil acidity.

Source: FinBIF species descriptions
Description text authors:

Ryttäri, T. SYKE. Updated by Luke 2023.

CC BY 4.0

The map represents observations of this taxon, but it may not be used as a distribution map.

squares
Observations
  • Total squares
Checklist
MR.1
Scientific name
Reynoutria japonica
Author
Houtt.
Vernacular names
  • japanintatar (Finnish)
  • parkslide (Swedish)
  • Japanese knotweed (English)
Identifier
http://tun.fi/MX.38240
Taxon rank
Occurrence in Finland
Status in Finland
This species is invasive
Regulatory Status
Finnish Regional Red List Category
  • 2019
  • 2010
Expert
  • Pertti Uotila
DNA barcode sequences
Reynoutria japonica
3 public records
Fallopia japonica
95 public records
Informal groups
  • Vascular plants