Japanese knotweed is a non-native, aggressive perennial plant
from Asia that spreads rapidly along waterways by means of
its root/rhizome mass, which is disturbed and distributed
in high water events and washes downstream to form new plants.
Any
stem node or length of rhizome over 1 inch long can form a
new plant wherever it is deposited.
Knotweed
threatens stream side areas due to the way it spreads and
its ability to overgrow and shade out other native vegetation.
It will even shade out blackberries!
Knotweed
is relatively new to the Clackamas River Basin (1950s-1960s).
Knotweed must be controlled before it is everywhere, as in
the case of blackberries, English Ivy, and Scotch Broom. It
has not yet reached the level of these other common invasive
and can still be controlled.
Help
us act now to control this invader.
