It is everywhere. Along the roads. In waste places. In an Audubon preserve in Concord. The Japanese Knotweed.
Sometime in the past someone introduced it, thinking it was an ornamental, and in small clumps, it might be. If my eye was unbiased, I would find it attractive.
But I know better, having seen it smother 8 foot dirt piles in waste places, and having had to root it out in new garden beds.
Terrifying that this strangler escaped, and even worse is the carcinogenic poison sprayed to kill it.
Gardening On Granite 