In El Salvador I saw a guy use two loops of rope to climb a coconut tree. He choked the first around the trunk, put one foot into the loop, then stood up (on the rope). Then, he did the same with the second loop of rope but with the bight hanging on the opposite side of the trunk for his other foot. After each step up he would reach down to retrieve the loop below and then repeat the process. Using this technique he went all the way up with no saddle and only a longer rope trailing behind him. At the top he passed the long rope through the canopy to lower bunches of coconuts down to his assistant. When he was done he tied the lowering line around his waist and, by using wraps around his own leg, he lowered himself to the ground.
Since then I've wondered if a climber could ascend a Palm or similar type stem by carefully stepping with some type of modified spikes onto the "lumps" of the trunk (without stabbing in too far). It would be faster, require less energy, and certainly be safer too.