This plant started as a ground vine, then found a post to climb up, and when the post ended it "exploded" in all directions, looking for sun or for something else to climb up.

Here is a look under the vines as it "explodes" in all directions. This is basically a poison ivy plant gone berserk

Poison Ivy Shrub in Summer and Winter

This is not very common, but important to know about: these poison ivy vines seem to have started out as ground vines and then grown into small trees.

Look closely: the trunk is a dead tree, covered with poison ivy vines. When they reach the top, they "explode" in all directions, looking for sun and for the next thing to climb up.

Poison Forms a Hedge

Massive Wall of Poison Ivy Shrubs at Seaside