Looks to me like it could be arrowhead, taro, or a caladium, did it produce
any sort of flowers, if so, describe.

I think it is a taro...the leaves are more broad than an arrohead. My elephant
ears ( a type of taro) bloomed last year, and the blooms look just like a
calla lily....white with a long yellow spath. Jerri

http://www.fringeweb.com/Ponds/JerrisPond