Willow Vines are large, immobile trees of Tra Sakinig's jungle with motile vines hanging from their branches, which try to strangle anyone who comes near. The vines and the tree are symbiotic: cutting a vine does no harm to the tree but frees whoever it has hold of, and killing the tree kills the vines shortly afterwards. The bigger the tree, the further its vines reach.

On the Wildfire Rescue, with the fire behind them, the herbalists' guide warned that the area was full of them and too thick to go around, so the party had to cut through one. A vine got Huxian round the neck and tried to wrestle her off the ground until Jun cut it in two, and Rodger's shots into the trunk set it leaking sap and the vines started falling away.