Somewhat thorny with pointed shovel-like leaves. In the fall produces purple like berries. Have no clue...just arrived in garden and is taking over.
I don't know this plant, but an image search for "triangular leaves" turned up Mile-a-Minute, Polygonum perfoliatum, which looks like a match to me. http://njaes.rutgers.edu/weeds/weed.asp?mileaminute
Wow...that is a "perfect" match. Thank you so much. Well, I guess a weed is anything that grows in the wrong place...and this vine is taking over.