Early cold snap rewards us with slew of trees dressed in crimson

The heavy September rainfall was a nuisance, but it is helping to bring out some vibrant fall colors in trees, especially the elusive reds.

"One of the components of fall color is soil moisture, and we're definitely there," said Doris Taylor, plant information specialist for the Morton Arboretum in Lisle.

Nature seems to be lining up to make the fall as colorful as possible, including a mixture of sunny days and cool nights that have stayed above 45 degrees for the most part, Taylor said.

That combination will especially lead to more crimson tones compared to last year.

"Last year we had so many dull leaves and a lot of yellow," Taylor said. "This year, because of the cold weather that came just before the warm spell, we're trapping in sugars in leaves and getting more reds and oranges."

The transition for leaves started at the end of September, and the major color changes should last for a few more weeks into October.

"We're pretty much right on schedule," she said. "In fact, every day more and more stuff is changing."

Taylor said the color changes depend on a number of factors: sunlight, moisture and chemical hormones.

"You can't make a tree with genetic traits for yellow turn red," she said.

For those who have forgotten their science lessons, here's a little recap of why leaves change colors:

Tree leaves contain chlorophyll, a pigment that makes them look green. The chlorophyll also helps with photosynthesis, the process by which leaves manufacture sugar from water and carbon dioxide by using the energy the chlorophyll has gathered from the sun.

As the days become short, the chlorophyll in trees is replaced at a slower rate. Eventually, other pigments can show through once the chlorophyll is depleted.

The bright colors, according to the Arboretum, depend on how bright the sunlight has been up until fall.

In general, honey locusts tend to turn yellow, whereas oaks are more burgundy or wine-colored.

Taylor said the recent short period of cold weather should also keep the trees looking brilliant for longer.

"It traps in those sugars that are going to make bright colors," she said. "So far we've been having great conditions."

For more information on the Arboretum, and a chance to read what "Color Scout" Ed Hedborn has found in the area, visit www.mortonarb.org.

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