Japanese Knotweed
not native
Knotweed is a robust perennial with cane-like, reddish-brown stems, commonly more than six feet tall. It spreads by rhizomes to form dense thickets. The large leaves, up to six inches long, are egg-shaped with abruptly pointed tips.
Branched clusters of very small, white to greenish flowers grow from leaf axils near the ends of the stems. This aggressive weed was recently introduced from Asia, perhaps as an ornamental, and now spreads rapidly in moist waste places, especially on the west side of the Cascades.
