I am definitely not the best person for identifications, but maybe it could be A. nobilis? Please wait for someone else to answer, because I am not 100%. :)

This makes me wonder if mine is really A. nobilis because mine looks nothing like Cast1

I have one that kind of looks like this, but I think the leaves are darker, and its a twilight hybrid.

If you dont find out soon go on wiki and open all the links for the plants to see which one looks like yours...
Sorry wasnt much help

A. spinnosissima or an A. humilis hybrid I'd guess.