They appear in both Deep Rainforest and Gas Rainforest once the player comes close to them. There are two variants of Hanging Vines. One of them is just a plant and can shear with a Shears to provide a Rope, and the other acts like a hostile creature (see image). It knocks out items from the players inventory when attacking. It also eats food left on the ground.
As their damage is low, one can simply place a high-stack item like Grass on the leftmost inventory slot and tank them. Placing a food item nearby is another option, as Hanging Vines prioritize eating food over attacking, so players can attack them without retaliation. As a bonus, using this method can cause a chain of leafy meat dropping and causing others to head for it, allowing an easy clearing of hanging vines.