What if trees could think...

...and they were evil?

...and they grew six kilometers tall?

...and their root systems spanned continents?

...and the green and red trees competed with each other for world domination?

...and they controlled the weather?

...and the trees could suck humans into their trunks, merge with them on a molecular level, telepathically communicate with them, draw information from their minds, implant post-hypnotic suggestions, and convince the humans that this "dipping" was pleasurable and addicting?

If trees were like that, well then you would have Doomtime: The War of the World Trees.

Tedron and Krake
The green trees are named Tedron and the red trees are named Krake. The giant trees grow next to each other but are separated by an impenetrable concrete wall. They desperately want to touch each other, for love or for war is not clear, and the only way to do this is to spread around the globe and meet on the far side. Um. OK. I'm not sure how spreading thousands of miles across continents and seas is easier than growing above or tunneling under a concrete wall, but this wall is apparently special. And magic.

Creed
The main character is Creed, and he lives in a city called Neo that is built honey-comb like into a hillside. Neo is the only city Creed or anyone else knows of, and everybody lives in Neo. One day, a stranger tries to kill Creed. Then trees start appearing in the valley below Neo. They've never seen trees before, but they seem to know all about them despite claiming not to.

Things happen. Then other things happen.
Doris Piserchia has a style of writing where she tells about things happening, but there's no plot. Events occur. Somebody does something. Then she drops the plot thread and picks up something else. It's herky-jerky and disjointed, a mess of ideas scattered like a Jackson Pollock painting. It doesn't work for me, at least not mostly.