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2012 Fall Issue 4 (October 12, 2012)

ArbNotes

October 15, 2012
By Jasmine Cutter

Fifth week means it’s crunch time at Carleton, but the stress level of students isn’t the only thing that is peaking right now.

As you walk around campus, this is the perfect moment to appreciate the brilliantly colored leaves you’re shuffling through. The fall color in southern Minnesota is currently at its prime, yet leaves are already quickly falling.
The brilliance of fall colors is determined by tree species and by the weather. The recent dry, sunny days and cool nights have produced a stellar show this year.

Temperatures that are low, but above freezing help destroy the green leaf pigment (chlorophyll) and stimulate the production of anthocyanins. Anthocyanins are leaf pigments that make the reds and purples seen on some trees.

These pigments reside in the cell sap of the leaves and are formed by chemical reactions between accumulating sugars and anthocyanidins. The more acidic the sap, the more brilliant the color.

A final class is the carotenoids, which produce the yellows seen when a leaf loses its chlorophyll.

These bright yellows are especially apparent in the leaves of the sugar maples and silver maples, several of which adorn the bald spot and the libe. Many sugar maples also display reds and oranges. Cottonwoods, cherry trees, and Aspens provide many of the other golden hues seen around campus. Flowering dogwoods, red oaks and sumacs bring deep, rich reds.

If you’re interested in a fun way to crunch through the leaves, the student naturalists are leading a trip TODAY! We will depart from the Arb kiosk in front of the rec at 4pm. Theme: Fall flannel fest. Flannel-wearing encouraged.

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