Populus tremuloides, also known as American Aspen, Quaking Aspen, Trembling Aspen, Quakies, Quakers, Popple, Golden Aspen, Mountain Aspen, Poplar, Trembling Poplar, Álamo Blanco, and Álamo Temblón, is a deciduous tree native to cooler areas of North America. It is a tall, fast growing tree, usually 20 to 25 meters (65 to 80 feet) at maturity, with a trunk 20-80 cm diameter. The bark is relatively smooth greenish-white to gray and is marked by thick black horizontal scars and prominent black knots.