The Devil’s Snare is a tree vine that wraps around it’s prey when it gets near. The more the hostage struggles it will kill them faster. It was also the second course guarding The Philosopher's Stone in the Underground Chambers.
The Devil's Snare is a gigantic plant with dark green vine-like tentacles.
Role in the film
The plant is next seen where Harry, Ron and Hermione land on. The vines wrap around them, but Harry and Hermione manage to relax and they slip out from the plant's grasp. Unfortunately, Ron panics, causing more vines to wrap around him. Until Hermione casts the sunlight spell which forces the plant to let go of Ron.