Any ideas what this is? Photo taken yesterday. The stalks are a purplish colour. There are thorns, spread far apart from each other. Shrub about 7-8 feet tall, in a field.
Sounds like a young Honey Locust tree. Long thorns. Surprisingly weedy.
They formed a wide clump about 20 feet long, so I don't think it's a tree ...
I don't see a single thorn in the images you provided.
It does look a lot like the invasive species that may go by the name Fallopia japonica now, and has been termed Japanese Knotweed and other common names. I don't believe this species is known for having thorns.
This plant can create huge masses via underground colonizing behavior, and especially likes riparian zones within which to spread - but doesn't necessarily require such conditions.
Ditto to Japanese Knotweed, definite. A seriously nasty invasive weed.
There are thorns -- I touched them. It's not Knotweed ... we have lots of that on our street, near a brook. Knotweed has a much sturdier stem than this did.
The seed panicles have fairly sharp bristly bits which can easily be taken for thorns when dry in autumn. And the stems are starting to rot down for the winter now. Sorry, but this absolutely is Japanese Knotweed. I know it far too well.
All I can say is that it looks nothing like the rest of the knotweed in this area right now.
Possibly this area has been treated with herbicide giving it a totally different appearance.
Easy solution is to collect some of this obviously vigorous plant, and bring it back to a location where lots of closeup imagery can be procured.
Take a pic of the whole patch while you are out there, too.
Nice thumbs, and appreciated. Just back from Savannah, and I've got my Bluegrass groove going - or Orchard Grass, as the case may be.