Japanese Knotweed
Polygonum cuspidatum

Adult
Japanese knotweed
Native to Asia, introduced to the United States as an ornamental. It invades roadsides, waterways, waste areas and pastures.
Rosette
Japanese knotweed
This creeping perennial has holow, reddish-brown, jointed stems. It grows from 2.5' up to 7' tall.
Leaf
Japanese knotweed
Flowers are small and cream colored borne in loose clusters. Rhizomes may grow upwards of 30' long and new plants may regenerate from rhizomes.
Leaf
Japanese knotweed
Leaves can be quite large.