The Emyn Muil:

A region of fairly barren cliffs on each side of the Anduin River. At the base of the cliffs were often bogs and fens: We can't get down, and if we did get down, we'd find all that green land a nasty bog, I'll warrant. (LOTR.627)

In earlier days the Emyn Muil were covered with trees, though they were gnarled and stunted, though by the time of the War of the Ring, few trees still lived.
Some way down they found a few gnarled and stunted trees, the first they had seen for days: twisted birch for the most part, with here and there a fir-tree. Many were dead and gaunt, bitten to the core by the eastern winds. Once in milder days there must have been a fair thicket in the ravine, but now, after some fifty yards, the trees came to an end, though old broken stumps straggled on almost to the clif's brink. (LOTR.629-630)