Kirkendall-Spring / Contorted trunks of Aspen trees (Populus tremula) in snow, near Brighton in Big Cottonwood Canyon, Utah, USA, February 2010

Floris van Breugel / Autumn colours of Aspen tree (Populus tremula) Sierra Nevada, California, USA. September 2009

David Noton / Autumn colours of the Aspen trees (Populus tremula) in the snow, near Muleshoe, Bow Valley Parkway, Banff National Park, Alberta, Canada. October 2009

David Noton / Autumn colours of the Aspen trees (Populus tremula) in the snow, near Muleshoe, Bow Valley Parkway, Banff National Park, Alberta, Canada. October 2009

Laurie Campbell / Looking up the trunk of an Aspen tree (Populus tremula) in autumn, Speyside, Scotland, UK, October

Jack Dykinga / Willow, Cottonwood and Aspen trees on the banks of the Oxbow Bend, Snake River, at dawn, Teton mountain range in the background, Grand Teton National Park, Wyoming, USA

Wild Wonders of Europe / Zacek / Aspen tree (Populus tremula) trunk with a line of snow on it, Oulu, Finland, February 2009

Shattil & Rozinski / Quaking aspen tree (Populus tremuloides) leaves and twigs coated with ice, over stream, Southern Colorado, USA, October

Shattil & Rozinski / Quaking aspen trees (Populus tremuloides) in autum, San Luis Valley, Colorado, USA

Shattil & Rozinski / Quaking aspen trees (Aspen tremuloides) in autumn, San Luis Valley, Colorado, USA

Shattil & Rozinski / Fallen Aspen leaves {Populus tremula} on rocks in river in autumn, USA

Shattil & Rozinski / Aspen tree {Populus tremula} leaves and trunks in autumn, USA