Land Plants - invasive

Japanese Knotweed (Fallopia japonica) on Apr 25, 2008

Submitter does not have a specimen

Description of specimen

I've watched this plant spread between the cracks of the sidewalk every time I drive by for the last year and a half. Since it is growing in such poor conditions (between the sidewalk and a building) the plant never gets too tall but spreads laterally along the sidewalk. I've never gotten out of my car to look real closely at it so it might be Himalayan knotweed or a hybridized version, but I've worked with invasive species for a while now and I can spot knotweed a mile away.