This stout, shrub-like plant forms large dense clumps that measure between 3-9 feet high.

The stems are reddish in color, ridged, jointed and hollow.

The leaves are alternate on the stem, broadly truncate at the base and 2-3 inches wide.

The leaf veins are often reddish and the petioles are 1 inch long and ridged.

The flowers bloom in late summer and are small and greenish white.

It reproduces by seed and by large rhizomes which may reach a length of 15-18 feet.

Japanese knotweed emerges in early spring and grows quickly and aggressively. It forms dense, nearly pure stands which crowd out native plants.