What could this vine be?

I bought this plant early this summer and let it grow outside-these leaves are about 12" in size and shaped like a medieval halberd or fleur de liss. it has a very thick woody vine. the petioles from vine to leaf are very hirsute with 1/4" wiry red/brown hairs.  I thought it was a philodendron but I couldn't find any in my books that look like this, is it a philo or something else. Also, it's putting out lots of long roots from the vine wih has creeped out of the pot leading me to hope/believe I could train it onto a big piece of driftwood...!

Any info would be appreciated!

Probably some sort of philodendron. I think the roots coming from the vine indicates it's ready to attach to something. If it is a phil the leaves could get much larger when it starts climbing.