Japanese Knotweed

Description:

JAPANESE KNOTWEED - Polygonum cuspidatum Sieb. & Zucc.

Polygonaceae - (Buckwheat family)

Perennial from long creeping rhizomes.  Stems are stout, reddish-brown, 4 to 9 feet tall, woody but die back at end of growing season.  The nodes are slightly swollen and surrounded by thin paper sheaths.  Leaves are short-petioled, broadly ovate, 2 to 6 inches long and about two-thirds as wide, narrowed to a point.  The flowers are greenish white to cream, borne in large plume-like clusters at ends of stems and in leaf axils.  The fruit is 3-sided, black and shiny.

Introduced from Asia as an ornamental, now escaped to become a weed of roadsides, waste areas, ditch banks, and pastures.

(Courtesy of Weeds of the West)

CONTROL STRATEGIES: