Tonguez
A suffusion of yellow
The World Tree can mean different things in different contexts. Sometimes, it is the air itself, where the dome of the branches are the dome of the sky, while the clouds fling across, high on its branches. It tree full of leaves and leafless are the seasonal cycles of the sky. It especially connotes the air anchoring and rooting in place within land.
The World Tree can mean other things also. It is reasonable for some of the Barbarian subclass mechanics to refer to airy and skyey effects, even with the concept of an ordinary tree reaching upward into the sky.
Now if they had done this it might have been okay, like when Marvel made the world tree into a Wormhole map and The Bifrost a high energy teleport machine - that parts fine. Barbarian teleporters with supernatural perception and foresight fit.
What doesnt is trying to shoehorn in some woody vines because entangling roots are tree-related.