I love v. thapsus also. I use it in pots where it's admired as a velvet leaved plant and then I explain what it's going to do when it flowers also. I find that I like it in pots when in flower also. The v. chaixii album is a perennial. A quick run through my seed bags tells me that I don't have any saved, but I'll have seed from the one that's currently flowering if you'd like some. T-mail a mailing address to me if you want some....
