Put more simply, on aircraft with constant speed (variable pitch) propellers there are two power variables as already mentioned, manifold pressure and RPM (which is related to propeller pitch). To draw a rough analogy with a car the RPM - controlled by the RPM lever - can be thought of as the gears (high RPM/fine pitch = 1st gear) and the MAP as the accelerator (controlled by the throttle as described above). As to how this relates to angry palm trees, try posting on the rotary forum if you haven't already.