The Aspens — One Tree, a Whole Hillside

Those white-trunked trees running in bands up the mountainsides are quaking aspen, and they are the reason several hundred thousand people drive this loop every autumn.

The leaves are on flattened stalks, which is why they tremble in the smallest breeze — that shimmer and the sound that goes with it is where the name comes from. In late September and early October they go gold, and occasionally orange and red, and this circle becomes one of the great fall drives in the country.

Here is the part most people do not know. An aspen grove is very often ONE organism. Aspens reproduce mainly by sending up shoots from a shared root system, so a whole hillside of trunks can be a single genetic individual — a clone. That is why you will see one patch of hillside turn gold a week before the patch beside it: they are different individuals, on different schedules. Once you know to look for that, you cannot stop seeing it.

Some aspen clones are among the oldest and largest living things on earth.

Aspens are also a pioneer species — they colonize ground that has burned or been logged, and then slowly get shaded out by the spruce and fir that follow. So those bands of aspen are a map of old disturbance: fires, avalanches, and the mining-era clearcuts we have been talking about.

Look at the trunks as you pass. You may see old carved initials and dates — and some of the oldest were cut by Hispano shepherds who ran flocks up here generations ago.