Its a cut leaved Bramble/Blackberry. Oregon Thornless produces viable seed that birds spread. Sometimes the progeny are thornless but many have small reduced prickles down the stems. This of course may be a cutting and actually be the variety Oregon Thornless of course. The person selling must have made a mistake.

sticking my neck out here but it does look exactly like my thornless blackberry. Just popped out & took a few photo's for you to compare, there in my photo album.

you got there before me Fractal but pretty much confirms it's a blackberry.

thanks all, that is so annoying: I got it from a big Centre selling perennials at 5 for £10.00, so while I can understand that customers might switch the labels you would think it would turn out to be another flowering perennial, not a bramble! Will move it to somewhere more suitable, once again many thanks

take your photo of plant back to the garden centre if possible, dont worry about not having a receipt & they should be obliging re replacement or refund although a replacement of what you wanted in the first place is better. A bramble is so far removed from an anenome that they should do the decent thing. Keep the blackberry, they are delicious ;-)