I googled it and tannia is one of several common names for Xanthasoma sagittafolia (whew!) Are you planning on growing it as an ornamental or as a vegetable? Some of the things I've read indicate it's very tasty if you know how to prepare it. It is also a very dramatic ornamental plant. It is of course an aroid, and is often discussed on the aroid forum--you could do a search on that forum or ask for specific information. I don't grow it (yet) so I'm reluctant to give advise, but I think it's not real challenging. I don't know how hardy it is, but people in much colder places than z7 grow them and store them in the winter.