Legolas can talk to trees, grass, and even stones.

‘May you have joy of the sight, my good dwarf!’ said Gandalf. ‘But whatever you may do, we at least cannot stay in that valley. We must go down the Silverlode into the secret woods, and so to the Great River, and then—’

He paused.

‘Yes, and where then?’ asked Merry.

‘To the end of the journey – in the end,’ said Gandalf. ‘We cannot look too far ahead. Let us be glad that the first stage is safely over. I think we will rest here, not only today but tonight as well. There is a wholesome air about Hollin. Much evil must befall a country before it wholly forgets the Elves, if once they dwelt there.’

‘That is true,’ said Legolas. ‘But the Elves of this land were of a race strange to us of the silvan folk, and the trees and the grass do not now remember them. Only I hear the stones lament them: deep they delved us, fair they wrought us, high they builded us; but they are gone. They are gone. They sought the Havens long ago.’

The Fellowship of the Ring, Book Two, Chapter 3: The Ring Goes South.