We've seen these bushes all along the roadways.  On Tuesday when we were traveling on 294, we were able to stop and get a picture.  I had to use my Seek app to identify it.  It told me it is Reynoutria japonica.  So I searched my reference books, and found this:

 

It is highly invasive, spreading by rhizomes, making it difficult to eradicate.  Some rhizomes are up to 10 feet deep!!!  But the good news is:  it stabilizes swampy soil, and grows in waste places;  so it does serve a few purposes.  It is also valued by beekeepers as an important source of nectar for honeybees.  The honey from Knotweed is called bamboo honey.  

 

And, my favorite part:  it's pretty!!!

 

HAPPY TRAVELS!!!