lesser knotweed (Persicaria campanulata)
A knotweed native to north India eastward, resembling other knotweeds but relatively small, growing to height 0.9m. In Britain lesser knotweed is a garden escape found on roadsides, riverbanks, waste ground and in woodland, mainly in the west. The leaves of lesser knotweed are semi-evergreen with veins arranged in a conspicuous and attractive grooved herringbone pattern. Like other knotweeds it spreads vegetatively to form clumps, but the Non-Native Species Secretariat considers it to be non-invasive.