Japanese knotweed

Perennial shrub reaching 4 m. Introduced to Québec and invasive. Grows in forests and in conifers. Flowers from September to October.

There are 1,523 observations of Japanese knotweed in Québec, mostly in Estrie, Capitale-Nationale and Montréal, and it has been reported in 16 of the 17 regions. They peak in August and September and become rare from November to March.