Autumn Leaves

(This 914th Buffalo Sunday News column was first published on September 28, 2008.)

A Variety of Maple Leaf Colors

Every season has its special qualities - spring for its new growth and returning bird migrants, summer for its vacation opportunities, even winter for its stark beauty - but fall remains my favorite. This is the season when we are treated to nature's spectacular display of color.

This summer's long series of almost daily thunderstorms has produced the greenest foliage I can ever recall. What effect that will have on the dates of the fall foliage peak remains to be seen. Letchworth Park naturalist Doug Bassett has suggested October 10-20 as the usual period for the park's best colors. I suspect that this year's healthy leaves will tend to remain longer than usual. There is great local variation, however, and you can already observe those lovely reds and yellows and occasionally even odd colors like bronze and purple mixing with the varying greens of our woodlots and forests.

With the expense of gasoline, you may not make it all the way to the Southern Tier this year, but any short trip to the countryside will disclose colorful woodlots. In fact a walk in one of our urban enclaves like Cazenovia Park, Forest Lawn or Elmtown Cemeteries, Tifft Nature Preserve or even along one of our tree-lined neighborhood streets can be intensely satisfying. At this time of year I always come back from such expeditions with a sense that I have been exposed to the sublime.

In her delightful book, Red Oaks and Black Birches, Rebecca Rupp explains why leaves change color and then fall. Shortened days and cooler nights encourage the formation of a kind of tourniquet where each leaf stem is attached to its branch. This cuts off the leaf's source of water and minerals, causing in turn the degradation and final disappearance of chlorophyll, the source of the leaf's green coloration. All summer that overwhelming green has masked the colors of other molecules but now those colors come to the foreground. "The yellows and oranges of birches, sycamores, and sugar maples," she says, "are due to carotenoids, the same cheerful molecules that color carrots, corn, egg yolks, and daffodils. Browns also may result from carotenoids or from tannins. Crimsons, scarlets, and purples are due to anthocyanins, which also color red cabbages, red roses, and purple irises."

Finally that same tourniquet reduces the grasp of the leaf stem until the wind carries the leaf away, leaving a wound where it was attached to its branch. The tree quickly plugs that wound with a cork leaf scar to protect itself from water loss. That leaf scar is as unique to its tree species as is the leaf itself and specialists refer to it for tree identification in winter.

The botanical processes are complex, the result a wonderful but far too brief period when Upstate New York takes on breathtaking beauty.

You can collect some of these leaves and preserve their colors for later contemplation in several ways. An older method is to flatten them between sheets of waxed paper and press this under an old towel with a warm iron. Finally, cut the waxed paper around the leaf, leaving a border to maintain the seal.

A second method is to dry leaves between sheets of paper toweling in a microwave. Experimentation is necessary to determine the optimum timing but between one and three minutes should be sufficient. If the leaves still curl, your time is too short; if they scorch, too long. Seal your dried leaves with an acrylic art spray.

You can also preserve leaves by soaking them in a mix of one part glycerin to two parts water for three to five days. No additional treatment is needed.

Saving the natural beauty of such leaves can be satisfying, but you may also wish to identify them. For most a quick comparison with a text silhouette is all that you will need. Excellent keys may be obtained from the Erie County Cooperative Extension Center in East Aurora, from libraries or from local bookstores.

When you collect leaves, associate them with the tree from which they fell. Its height and shape, its bark color and pattern will help you to identify that species in winter when those leaves are buried under the snow.-- Gerry Rising