Only spotted in the Hollow Bough, the aptly named Stabber Vine is very aggressive and should be approached with caution. The source of these "vines" is still unknown as is their exact nature. Is it a plant or animal, we just don't know.
~ Miner's Manual Description
The Stabber Vine is a hostile form of life encountered only in Hollow Bough. It is an aggressive and much more dangerous form of its stationary brethren, and will actively attempt to hit Dwarves.
They will spawn in clusters of 3 in the same spot, and have quite a large range. If a player wanders near, one of the clawed vines will lash out with lighting speed and impale them, dealing heavy damage. If the dwarf stays in their range they will alternate attacking with the other claws. They can be destroyed by focused fire.