The correct term for tree worship is dendrolatry. In ancient India it was widely believed that spirits or gods inhabited trees, particularly large, old and gnarled ones, and tree worship was an important part of popular religion as it still is in India.
The Greeks had similar beliefs and called tree spirits dryads. In the Tipitaka they are called rukkhadevata, vanadevata, or aramadevata, (A.III,369; M.I,307; S.IV,302). Some trees, called wishing trees (rucarukkha), were believed to answer prayers or more correctly, the gods in such trees did this. Likewise the healing power of certain herbs were believed to be due to the gods that inhabited them.
There is no place in the Tipitaka where the Buddha endorsed the worshiping of trees the way he occasionally did for the gods. In the Dhammapada he said ‘Gripped by fear people go to sacred, hills, woods, groves, trees and shrines. But these are not a safe refuge, not the best refuge. Not by going there is one freed from all suffering.’ (Dhp.188-9). Several Jataka stories poke fun at tree worship.