An Abundance of Male Trees Is Upping Your Allergy Misery

Aimee Curtis of Greater Greater Washington writes that cities have long preferred to plant male trees because they tend to be cleaner than their female counterparts—not dropping fruit and seeds all over the sidewalk. However, as a consequence the pollen that the male trees release has nowhere to go but into the air. Curtis writes, that in a gender balanced situation, the female trees would soak up that floating pollen.

Horticultural epidemiologist Tom Ogren traces the modern preference for male trees to around 1950, when the USDA released a book that promoted planting male trees over female trees for easy, litter-free maintenance. The idea caught on with private homeowners, nursery suppliers, and city planners....

Favoring male trees isn't a bad idea in itself, and Ogren believes no one had any bad intentions. "But when a city does this on a massive scale, it has a huge impact on the health of the people who live there," he said to Governing. Ogren, who developed the Ogren Plants Allergy Scale (OPALS) used by the USDA and American Lung Association, says planting more female trees will reduce the pollen count in a city.