Olvar

The Olvar are all inanimate forms of life in the world of Arda specifically referring to plants.

Trees are apparently considered to be of the highest rank of the Olvar and the Ents are their appointed guardians as well as other growing things.

History
The Olvar have existed in the world since the Spring of Arda with seeds planted by Yavanna and much of her early work was marred by Melkor. With the unexpected creation of the Dwarves, Yavanna feared for the safety of trees and sought the advice of Manwë who allowed many spirits to walk amongst them, giving rise to the Ents.