Tree gender and pollen counts

Are seasonal allergies getting worse because we’re planting too many male trees? The “holes” in the pollen map are also rather interesting. I’m assuming they reflect a lack of data rather than a lack of pollen.

One of the most memorable posts on Pruned, I think, was written way back in September 2005, when Alex took a look at what he called “litter-free landscapes and the politics of pollen.” He quoted horticulturalist Thomas Leo Ogren at length:

In our urban landscapes we now have the most manipulated kind of city forest ever seen. In the past twenty years landscapers have grown inordinately fond of using male trees. In dioecious species (separate-sexed) there are separate male trees and separate female ones. Female trees and shrubs do not produce any pollen, ever, but they do produce messy seeds, fruits, old flowers, and seedpods. Landscapers and city arborists consider this female byproduct to be “litter”, and they don’t like to see it lying on our sidewalks.

In other words, urban landscapers over-utilize pollen-intensive plantlife—which, in turn, wildly amplifies seasonal allergies. What if you didn’t need more boxes of Claritin, then—you need a more informed city parks department?


from “It’s the Trees,” by Geoff Manaugh, BLDGBLOG, 11 April 2010

Originally published at culture-making.com.

Add Your Comments