The old man of the mountain is a tricky one. Those hairs that you see are not hairs at all; they are modified spines which themselves are modified leaves! This armor keeps the troll safe from all kinds of weather.
The ol' man has also been deceiving us when it comes to wood (no pun intended)! Wide-band tracheids (WBT) are a special kind of wood that not only support this cactus but also store water. Since this wood lacks fiber, it can easily contract during drought, thus preventing it from caving in on itself.