JACKSON, Wyo. — Today, Sept. 22, is the first official day of fall. Throughout the season, a magnificent display of autumnal foliage can be seen across the valley.
The National Park Service explained the science behind the phenomenon of leaves changing hues:
“In fall, the length of daylight and cooling temperatures cause leaves to stop generating food. Chlorophyll breaks down and the green color disappears allowing other pigments to become visible like carotenoids that produce brilliant yellow and orange leaves. Some leaves will generate red pigments, anthocyanins, due to excess water and sugars. Temperature and moisture control the intensity and duration of the colors.”
In the coming months, keep an eye out for these spectacular leaves:
Quaking Aspen: These leaves are usually one to two inches across, their trees have white bark and grow in large stands.
Quaking aspens grow throughout Grand Teton. Look for them near water, on mountain slopes, or tucked in with evergreens. Aspens tend to ‘quake’ or ‘dance’ when the wind blows through them. In autumn the trees appear to shimmer as sun dances off their yellow leaves.
Where to find them: Willow Flats Overlook, Snake River Overlook, Oxbow Bend, and Two Ocean Lake.
Narrowleaf Cottonwood: These leaves are usually two to five inches long, the bark is yellowish-green to grayish brown, smooth on upper portions and furrowed into broad, flat ridges on older lower portions.
Where to find them: Cottonwoods are native to wetland and riparian areas and can be fund along the banks of streams and rivers. They are present around the Gros Ventre River, Cottonwood Creek and Schwabacher’s Landing.
Black Hawthorn: These leaves are usually one to two inches long, their bushes grow 6-30 feet tall and have 0.5 to 1-inch thorns.
Where to find them: Black hawthorn can be found in most moist areas along streams, or in an open area that receives full sun. Look for them at lower elevations in the park. They can be seen around Moose- Wilson Road and Laurance S. Rockefeller Preserve.
Willow: These leaves can be two to five inches long and their bushes grow seven to nine feet tall and wide.
Where to find them: Willows grow in damp, marshy areas. Look for them near springs, around ponds, and in areas of low elevation. When viewed from above, their colorful leaves appear to create a bright carpet across the valley. They can be seen at Blacktail Ponds Overlook, Willow Flats Overlook and Christian Ponds.