Looks like someone caught a mile-a-minute vine before it took over. They hung it on a branch to dry it out. This prevents it from rerooting. Good technique.
Here's a shot of it courtesy of the National Park Service:
I also found this video that walks you through how to identify it. Some of the key characteristics are its long "petioles" (the stalks between the vine itself and its leaves) and its leaves, which are almost perfect triangles.