Your allergies are bad because of tree sexism

Photo: Hannes Flo (CC BY 2.0)

I'm one of those people who's damn near allergic to everything — or at least, according to my doctor, to all forms of dust and tree pollen, which might as well be everything. This was particularly frustrating at the start of the COVID-19 outbreak this spring, as every day I woke up with a scratchy throat or runny nose I immediately assumed the worst. (Don't worry, I'm fine; it was allergies every god damn time.)

While I tend to thrive better in cities that offer some respite from our botanical oxygen-pooping friends, I recently learned that American urban planning generally favors male trees, which produce more pollen. From Atlas Obscura:

[W]hen [Tom Ogren, horticulturalist and author of Allergy-Free Gardening: The Revolutionary Guide to Healthy Landscaping] studied frequently landscaped plants in other cities, he noticed the same thing: males, all the way down. “Right away I started realizing there was something weird going on,” he says. While tracking down the origin of this trend, Ogren stumbled upon perhaps the first trace of sexism in urban landscaping in a 1949 USDA Yearbook of Agriculture. The book advised: “When used for street plantings, only male trees should be selected, to avoid the nuisance from the seed.”

Urban forestry’s apparent sexism seems to boil down to our distaste for litter. The USDA reasoned that tiny allergenic spores are likely to be blown away by wind or washed away by rain, making pollen an easier civic task to manage than, say, overripe fruit or heavy seed pods that would need to be cleaned up by actual humans.

I guess I knew that all that pollen dusting my patio was technically tree sperm, but I never really thought about it. But of course, the USDA's rationale for prioritizing male trees — that they're easier to clean up — isn't entirely true either:

In a cruel kind of irony, if urban landscapers had prioritized female trees in the same way, neither pollen nor unsightly seeds or fruit would be much of an issue. “If they had done it the opposite and planted hundreds of female trees with no males, it would have been just as sterile and tidy, without any pollen,” Ogren says. “Female trees don’t make fruits or seeds if there are no males around.” A large tree will scatter the majority of its pollen within 20 or 30 feet from its roots, Ogren says, so relatively isolated female trees simply wouldn’t bear much fruit.

Another argument proffered against female trees is that certain ones can produce an unpleasant odor. For example, when a lady gingko tree is in heat, it produces an odor not dissimilar to rotting fish or vomit. Ogren cedes this point. But if a city planted only female gingkos, decreasing the chance of fertilization, there would be neither pollen nor its infamously noxious postcoital odor, he says.

The whole article is weirdly fascinating look at how botanical sexism seeps into and shapes our societal planning.

‘Botanical Sexism’ Could Be Behind Your Seasonal Allergies [Sabrina Imbler / Atlas Obscura]

Image: Public Domain via Needpix