CORVALLIS, Ore. – The Douglas-fir, state tree of Oregon, towering king of old-growth forests and one of the tallest tree species on Earth, finally stops growing taller because it just can't pull water any higher, a new study concludes.
This limit on height is somewhere above 350 feet, or taller than a 35-story building, and is a physiological tradeoff between two factors in the tree's wood - a balance between efficiency and safety in transporting water to the uppermost leaves.