Populus tremuloides Michx. American Aspen
Native to a large area of N. America, in Canada south of the tundra, and western United States from Mexico northwards. Occasionally cultivated in Europe. Height to 30m (100ft) in the wild but usually half that in cultivation. Flowers open in February and March, male catkins pinkish with long silvery hairs about 5cm (2in) long and more slender than those of Aspen (P. tremula); females also with silvery hairs also about 5cm (2in) long. Fruiting catkins are about 15cm (6in) long and release white cottony seeds in May. Leaves are almost circular and have fine teeth on their edges (not wavy edges as P. tremula). They have flattened stems causing them to quake in the wind. Bark is paler and yellower than P. tremulu and bark on voung trees has horizontal dark marks. Zone 1