The leaves are circular or triangular ... around 2.6 million years ago. The aspen tree is found in Canada, northwestern Alaska, and southeast through Yukon and British Columbia.

Thin aspen leaves rustling in the crisp Colorado air ... At left is a typical warm weather leaf from a southern live oak tree. At right is a leaf more typical of cooler weather, from a sweetgum ...

This wound leaves open the possibility of diseases or pests entering the tree,” the Leave No Trace website said. Aspen trees are particularly vulnerable because they are linked together ...

It was an aspen tree, not one yet showing off the shiny leaves we seek this time of year. Maybe they would never show. “I saw the orange hue on the bark,” said Korb, who has researched the ...

"They look like tree trunks to us ... In mid-summer, the aspen's leaves are pretty much at their largest. "And there's just a really nice shimmering quality to Pando when you walk through it ...

A quaking aspen tree, Pando aspen, in Fishlake National Forest ... In the mid-1970s he walked through it and compared leaves on neighboring trees, using them to distinguish between stems ...

Aspen has distinctive, almost-circular leaves with flattened petioles or stems. This flattening causes the leaves to tremble or flutter in the slightest breeze, thereby giving the tree one of its ...

Beyond the aspen In Colorado ... Bicyclists pedal past an elm tree whose leaves are beginning to experience autumn changes in Washington Park in 2003. (Cyrus McCrimmon, The Denver Post ...

The tree was once common but deforestation ... foliage in the summer and striking golden yellow leaves in the autumn Trees for Life said Aspen was an essential part of the ancient Caledonian ...