Japanese knotweed is a dense growing shrub reaching heights of 10 ft. (3 m). The semi-woody stem is hollow with enlarged nodes. This weed invades disturbed areas such as roadsides and stream banks. Reproduction occurs is mainly vegetative; any stem fragment that contains a node can start a new plant. The dense patches shade and displace other plant life and are exceptionally hard to eradicate. Japanese knotweed is prohibited in New York; it is illegal to purchase, sell, transport or propagate.