Itchy eyes, a congested nose, sneezing, wheezing and hives: these are symptoms of an allergic reaction to the environment caused when plants release pollen into the air, usually in the spring or fall. A colloquial term for seasonal allergies — and the inflammation of the nose and airways (and all that comes with it) — is hay fever, but that’s a misnomer — those suffering from hay fever almost never get a fever, and hay is not the culprit. Doctors and researchers prefer the term “allergic rhinitis.”

Tree pollen, grass and other environmental evils

About 40 million Americans suffer from seasonal allergies. The most common culprit is pollen — that dastardly (but necessary) powder released by trees, grasses and weeds to fertilize the seeds of neighboring plants. As plants rely on the wind to do the work for them, the pollination season sees billions of microscopic particles hit the highways of the air, and many of them end up taking a wrong turn up our noses and into our mouths.

Spring bloomers include ash, birch, cedar, elm and maple trees, plus many species of grass. Weeds pollinate in the late summer and fall, with ragweed being the most volatile. The pollen that sits on brightly colored flowers, it is interesting to note, is rarely responsible for hay fever, because it is heavier and falls to the ground rather than being borne in the air. Also, bees and other insects carry that pollen directly from one flower to the next without ever crossing paths with vulnerable human noses.

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By Heather Whipps
May 31, 2014
livescience.com