try your experiments on canadian
goldenrod, momentarily the greatest pest here in central Europe - even
the smallest root piece can re-grow to a new plant, thousandfold - you
just could say "callus differentiation"

Will give it a try. First have to identify it

you can't oversee them, start flowering in the moment:

flowerheads golden-yellow, each with 10 - 17 short rays, in broad
pyramidal panicles, and thoroughly covering vast semi-dry sunny areas
and dominating all other plants

.... and keep in mind, all thistles are bi-annual: when you cut them
before ripening they cannot subsist

I am beekeeper with some other hobbies, have a look at

http://www.flickr.com/photos/71092423@N00/

cheers