A field botanist's take on the pollen blitz

By Carol Clark

The first day of spring was more like summer at Emory’s Oxford College campus, 40 minutes east of Atlanta. It was the seventh straight day of highs above 80 degrees, breaking the March record for an unbroken stretch of such high heat in the Atlanta region.

Biology professor Eloise Carter and students in her field botany course returned to the lab from a trip to nearby Oxhouse Lake, sweaty and dusted in pollen. As the students laid out specimens of flowering plants they collected, Carter brought out her iPhone to show photos to another biologist in the department.

“It’s pollen,” she says, showing what looked like a sandy beach, but was actually tree pollen coating the surface of the water along the lake shore.

The count of 9,369 particles of pollen per cubic meter of air on Tuesday was 55 percent higher than the previous record, set in 1999. A mild winter, leading up to a hot spring, has blown back the clock, driving the blitz of allergens from trees that are pollinated by wind.

Instead of tree pollination extending as usual from February to May, “it’s been telescoped down,” Carter says. “It’s pretty extreme.”

Carter, who has been leading students on biology outings since 1988, has been collecting data for 25 years on what plants flower when around Oxford, Georgia.

The loblolly and short leaf pines are shedding pollen now, on their usual schedule. But flowering that is usually spread out over a month for 10 different varieties of oak has been collapsed to the past few days, she notes. Mulberries, box elders, sweet gums, birch and sycamore are also currently in the mix.

“I’m wondering what’s going to happen downstream from now,” Carter says. Late in the semester, will there be any flowering plants left for her field botany students to collect? Perhaps plants that normally flower in the summer will blossom and fill the spring void, she speculates.

Plants decide when to flower based on the length of day and the temperature. “While plants may respond to temperature changes, insects may or may not,” Carter says. “If you get a real disconnect between plants and their pollinators that may affect the reproduction of rare plants, agriculture plants and others. Plants living on the fringe of their range might even be eliminated.”

Top photo by iStockphoto.com.

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