I have to agree with Mark. T. ciliatum can be dreadful planted out in the garden. I planted a couple in my last garden and after less that ten years they had multiplied into hundreds and taken over an area about 20 years square. We dug up bucket after bucket of golf-ball sized tubers, which had to be burnt, but still never cleared them. That is all in the UK in a garden which regularly suffered cold winters and on heavy clay soil. Never again!!! best regards, David Victor