Species of tall, fast-growing tree native to cooler areas of North America. The name refers to the tendency of leaves to tremble or quake in even a slight breeze due to their flattened petioles. It is most easily distinguished from a similar European species, P. tremula, by the shape of its leaves, which have more pointed tips, and by growing via root suckers: it propagates itself primarily through root sprouts, and extensive clonal colonies are common. The leaves are food for various insects. A substance in the bark was extracted by Native Americans and the pioneers of the American West as a quinine substitute. The soft, weak wood is used as paper pulp and for other purposes.
