Giant knotweed – Reynoutria sachalinensis

Giant knotweed is native to northern Japan, the southern Sakhalin in Russia and the Kuril Islands. It was introduced to St. Petersburg in 1864 and to Great Britain in the 1860s. The plant was exported to New Zealand and Australia in 1935. The giant knotweed was imported to Europe as a horticultural plant, but at one time it was also recommended as a forage plant.

The giant knotweed is widespread in Europe. So far, it mainly occurs in the southern areas. The occurrence of large knotweeds has been concentrated in urban and sparsely populated areas. Typically, it spreads as pieces of rhizomes in soil which is used as landfill in parks, yards, and road construction. In the garden depris it also spreads to riversides.