Usually, the tip of the leaves are pointed, but unusual leaf shapes are not uncommon. While the leaf blades of the quaking aspen are indeed beautiful, it is their flexible leafstalk that attracts so much attention. The long leafstalk of quaking aspen is flattened, and is held perpendicular to the blade of the leaf. This captures the wind and results in the "trembling" behavior of the leaves, which causes both the shimmering appearance as well as the audible "whisper" of the leaves while in motion.