I beg to differ. After reading your reply, I set out to verify it, and found only 2 possible coroboratons. Since I was hard pressed to accept that a “mature” version could differ so radically from what we are accustomed to seeing when thinking of a Syngonium podophyllum, I went to the Alfred Graff and quite by accident, while looking at the syngoniums, came upon the xanthosoma wenlandii which is exactly what I have. I found multitudes of corobarating pages on the web, hence I respectfully sumbit that this is a xanthosoma wenlandii whose identity was discovered thanks to your comments.

That is Syngonium podophyllum, Nephthytis or Arrowhead Vine. You have the mature version of the plant. Young plants have heart-shaped leaves. http://plants.ifas.ufl.edu/node/440