Sunday, September 21, 2003

By Lillian Thomas, Post-Gazette Staff Writer

Before humans used chlorophyll and carotenoids to explain fall leaves, they drew on a mother's grief over the kidnapping of her daughter or the persistence of a group of bear hunters to account for the spectacle of summer green giving way to autumn's fiery blaze.

Dan Marsula, Post-Gazette illustration Click photo for larger image.

Fall colors are one of nature's irresistible works. After autumn officially begins Tuesday, Western Pennsylvanians will start taking long weekend drives to look at dying leaves. They will consult Web sites devoted to the subject, and they'll attend events dedicated to it.

And they'll read articles that appear as regularly as the leaves themselves explaining that in the fall, trees stop producing chlorophyll -- the substance that gives leaves their green color -- unmasking the other colors.

Those golds and oranges are made by carotenoids and xanthophylls, while the reds come from anthocyanins.

But once upon a time, people thought the reds were produced by the blood of a monster bear hunted all the way up to the sky.

A Seneca myth recounts that each autumn, a band of brothers and their small dog track a gigantic bear terrorizing their community. They chase him up and up, into the dark night sky.

They kill the bear, and its blood falls from the heavens, coloring the leaves of the maple tree scarlet. As they cook the bear for a meal, fat from the fire drips down, turning other leaves gold and orange.

The story also was linked to the constellation Ursa Major, blending the celestial indications of seasonal changes with the terrestrial. As Earth repositions itself during the year in relation to the heavens, the bear is killed in the fall, appears to arise again in the spring, and the hunters begin their chase anew.

The Greeks explained the advent of fall with a wrenching family story.

The goddess Demeter lost her beloved daughter, Persephone, when the king of the underworld abducted her. Demeter was so grief-stricken that she neglected the plants of the Earth, which began to wither.

In one version, the leaves on the trees saw her despair and turned red, orange and gold to try to lift her sadness. When it deepened, they, too, despaired and the leaves dropped to the ground.

Other cultures weren't so mournful in their explanations. Many northern countries, from England to Japan, attributed the coming of the cold to an assortment of magical creatures -- frost fairies, the Frost King, the Snow Queen, Old Man Winter and the English version, Jack Frost.

Jack is usually portrayed as a mischievous guy who pinches or paints the leaves, then spreads cold and frost about.

In another Indian tale, Winter is a tyrant who orders all the trees to drop their leaves so not a single sign of spring will be evident. But conifers defy Winter, retaining their spring green. They are joined by Oak, who though he is not of their kind, agrees to fight Winter, vowing to hold on to his leaves even as they turn brown and frayed.

"I like that one," said Kathleen Allen, a University of Pittsburgh archaeologist who studies Iroquois cultures. "I think of a red oak at the corner of Phipps [Conservatory] that I pass by. Sometimes it has kept its leaves all winter, and drops them just as spring arrives. It's nice to see it hanging on, with some leaves, even in the middle of winter."

The modern-day storytellers tend to be academics like Marc Abrams, a Penn State tree physiologist and fall color expert. Abrams has studied how precipitation and temperature affect the timing and brilliance of fall colors for years. He tells the seasonal story of chlorophyll and carotenoids to students and reporters.

The start of fall at 6:47 a.m. Tuesday comes during the crucial period for the leaves, he said.

The latter part of September into early October is the time when climate conditions set the palette for the year, he said.

"Ideally what would be happening, is that things would start drying out now. Temperatures would start to get significantly cooler, getting into the 30s at night. We don't want a hard frost, but we do want things to get quite cool."

He said the unusually wet summer this year is not a major factor.

"I'm not anticipating that really to be a negative on the trees," he said. "Some of the early indications are that colors are looking pretty good on the maples. The wet summer actually is probably a positive, in terms of how healthy and vigorous trees are. But we need that to stop now."

The rain that the remnants of Hurricane Isabel dumped on the region last week shouldn't cause much of a problem.

"Luckily, leaf color is quite resilient," said Abrams.

For information on fall colors in Pennsylvania, visit www.fallinpa.com. The colors typically peak in the northern part of the state during the first two weeks of October; in the central part during the second and third weeks of October; and in the southern part during the last two weeks of the month.

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