Spring is in the air, and so is pollen, making our eyes itch and our noses twitch, and making for long lines at the car wash.
Marjorie Rachlin wrote in 2019 about the oak trees that are largely responsible for the misery of spring allergy sufferers around here. Last week, I spotted something different: tiny puffballs of pollen, quite unlike the long catkin threads from oaks.
A neighbor I met pulling out of her driveway thought it was from a beech tree. She was right.
Pollen-bearing catkins on a male beech tree. (photo from northernontarioflora.ca)
Oak and beech pollen is dispersed by wind for pollination. And right now in DC, pollen is permeating our air and causing the 20 percent of us who suffer from seasonal allergies to lay on the allergy medication.
Pollen counts have been higher than normal, but our definition of normal is shifting due to climate change. The Harvard School of Public Health warns that “warming temperatures and increasing carbon dioxide in the air from fossil fuels are contributing to longer and more intense pollen seasons.” And according to the U.S. Department of Agriculture, “pollen seasons start 20 days earlier, are 10 days longer, and feature 21% more pollen than in 1990 – meaning more days of itchy, sneezy, drippy misery.”
Pollen, of course, also plays many useful roles. It makes the green things that feed us, shade us and sustain us reproduce and grow. And, it aids in our understanding of the history of plant life on earth.
Colorized scanning electron microscope image of pollen grains. (Dartmouth College image)
Pollen’s outer layer, called exine, is nearly indestructible. “Treatment with intense heat, strong acids, or strong bases has little effect upon it,” Britannica explains. Because of its wide dispersal and near indestructability, pollen becomes part of the geologic sediment. And its composition and structure are so distinctive that a plant species can by identified by pollen granule alone.
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