Populus simonii, Simon's poplar, Simon poplar, or Chinese cottonwood, is a species of poplar native to northeast China and to Mongolia, and commonly planted as a street tree in cool temperate areas of Europe. There have been introductions into North America, South Africa, Australia and New Zealand.
The birch poplar is a tree up to 20 meters high with a narrow crown and a diameter of up to 50 centimeters at chest height. The trunk bark of young trees is greyish green and later turns dark gray and furrowed. The twigs are bare, reddish-brown, thin, and round petioles; stronger shoots are often angular. The buds are brown, elongated, pointed and sticky. The leaves have a 1 to 2 centimeter long stem. The leaf blades are rhombic-elliptical to obovate, 3 to 12 centimeters long and 2 to 8 centimeters wide, briefly pointed with a rounded to wedge-shaped base and serrated leaf margin. The upper side of the leaf is dark green and bare, the underside light green to whitish and also hairless.