Two months after the fall color of aspen and maple leaves faded from the mountains, Tucson is having its annual “second autumn” — with leaves of cottonwood trees glowing in golden hues along watercourses around the city.
You can catch a glimpse of the early-winter color show at various spots near Tanque Verde Creek, the Rillito River and other stream beds.
One prime place for a good view: Tanque Verde Creek east of the North Craycroft Road bridge.
“I like to think that just the sight of a grove of cottonwoods in the distance can soothe the soul,” said Erik Rakestraw, a horticulturist at the Arizona-Sonora Desert Museum.
A BIT ABOUT COTTONWOODS
“These gentle giants can attain massive size and are important to man and animal alike,” Rakestraw said. “Lucky is the desert traveler who finds respite beneath these stately trees, where the air can be several degrees cooler beneath their canopies and the leaves seem to dance on gentle breezes.”
Trees of the Fremont cottonwood species, which are native to the Southwest, typically grow near rivers, washes and wetlands. They can reach heights of more than 100 feet and have heart-shaped leaves.
LATE SEASON COLOR
Why do the leaves of cottonwoods change from green to golden yellow so late in the season in the Tucson Valley — long after most leaves in the nearby mountains have lost their luster?
“Because the tree is deciduous, its leaves will turn yellow when cooler weather stops chlorophyll production,” Rakestraw said. “This just happens a little later down in the valley. Leaves will eventually fall, however, and it may be less than six weeks before the tree puts out buds again.”
Here’s one reason to get a look at the leaves this year: “Fall color is only seen in regions with gradual temperature changes,” notes a website compiled by the Master Gardener Program of the University of Arizona Pima County Cooperative Extension. “In Tucson, some years the change to cold season temperatures may occur too abruptly, and the leaves drop without ever turning gold.”