Of or pertaining to the aspen, or resembling it; made of aspen wood.
source: Webster 1913
noun
any of several trees of the genus Populus having leaves on flattened stalks so that they flutter in the lightest wind
source: WordNet 3.0
One of several species of poplar bearing this name, especially the Populus tremula, so called from the trembling of its leaves, which move with the slightest impulse of the air.