Here's a picture of the roots of this plant.

Taro?

I believe Taro is just another name for EE. I suppose it is a relative since the leaves are the same. I am in zone 7 and my EE get over seven feet if in the ground.

It could be any one of a number of plants in the family Araceae (Arums) of which Taro is a member. Many of the plants in this family are often referred to as elephant ear. Most, but not all, have a corm or tuber and the flowers are normally inconspicuous. It looks very much like Taro that I have grown in the past. I planted what is commonly called EE this year in large pots around my pond and they look exactly like these. Sorry, rambling.

I like the plant because it makes such a nice backdrop for our pond. But it is so aggressive it has choked out many of the other plants as it spreads and takes over.