They are little more than parasitic vines that attach themselves to a tree and coordinate to hijack the plant's latent motor functions. Then it's a simple matter of working together to 'animate' the tree's trunk and branches to give it a full range of motion. Each Gnarl operates the opposite side of the tree, and synchronously conjoin their tendrils to form a 'mouth' through which wind can blow to produce sound. The tree can talk but it only does so with the joining of it’s tendrils.