Science

Sexism is NOT to Blame for Your Allergies!

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Have you noticed that over the past decade or so your allergies have gotten worse? If so, you’re not alone — lots of people have been sneezing more often these days. So what’s going on? You might immediately think “well obviously it’s climate change, the reason why just about everything is worse these days” but what if I told you that the answer is ACTUALLY….sexism.

That’s right, SEXISM. BOTANICAL sexism. Tree misogyny. Misogytree. 

Maybe you’ve heard this before: allergies are bad because city planners back in the 1950s decided to plant all male trees, because female trees produce fruit, which falls to the ground and gets messy. With no lady trees to snag the pollen coming from all these male trees, there’s now more pollen in the air and hence worse allergies.

Wow! Fascinating! Except…it’s not true.

This blew me away because years ago I read about “botanical sexism” in Scientific American, a magazine I tended to trust. I went back and found the article in question from 2015 and saw that it was a “guest blog” by Thomas Leo Ogren. Ogren is also featured in the Atlas Obscura article about botanical sexism written in 2019 and the Guardian article about botanical sexism published in 2020. In fact, he is the sole voice of authority in every article I could find about this topic. Literally no other scientists are ever cited.

And the reason why? Well, Dr. Sarah Taber is a crop and food safety scientist who broke it down on Twitter in response to this Tweet (account since suspended):

“i recently learned (to my dismay) that female trees are purposely not placed in urban areas. this is bc capitalism doesnt want female trees to bear free fruits. you can also thank capitalism for pollen season due to too many male trees producing pollen w no females to fertilize”

I love that it used to be about “sexism” but now it’s about “capitalism.” Genius. 

Taber doesn’t get into this in her thread so let me just say up front that this person is confusing different meanings for the word “fruit” — female parts are “fruit” but that could mean an orange or, say, the little helicopter things that fall off maple trees. And the reason that Ogren (the only scientist making this argument) cites is that the “fruit” isn’t desirable in an urban environment because of the mess it makes.

Anyway, Taber points out that Ogren argues that the pollen issue in urban areas would be better if we planted more female trees, because the female trees would suck up the pollen. But, that’s not really how it works. Trees produce clouds of pollen because pollen is cheap to produce and wind pollination is imprecise. No amount of tree pussies will be enough to vacuum all the tree sperm out of the sky.

Taber highlights the fact that most trees aren’t male — the plurality of trees have both male and female parts on the same plant. The most common dioecious (all male or all female) urban tree is the gingko, which, yes, produces a lot of messy fruit so most urban planners go with male.

Other experts seem to agree with Taber. Way back in 2003, Cecil Pounder, a research horticulturist with the Mississippi Agricultural and Forestry Experiment Station, pointed out that “male plant theory does not account for the diverse plantings of the eastern United States. In the East, large numbers of male clones of trees or shrubs are not needed because many varieties thrive naturally in the region. Pounders also said many of the most common trees, shrubs and vines in this area have few male forms available.”

A lot of articles written by or about Ogren say that he traced the problem of male trees back to a note he found in the 1949 USDA Yearbook of Agriculture: “When used for street plantings only male trees should be selected, to avoid the nuisance from the seed.” But Timothy Burke, professor of history at Swarthmore College, happened to get his hands on that book and found “there is no general advice in there that only male trees should be planted in urban areas,” but just very specific advice about specific plants, like “Cottonwood (because female cottonwood trees make a mess); boxelder (because an insect that lays on female boxelders & overshelters inside homes if they’re nearby); gingko (because the fruits); Carolina poplar (“because the female has disagreeable fuzz”, which is amusing).”

So even the basis of Ogren’s entire schtick is exaggerated. Meanwhile, I could find no decent studies that break down how many trees in a particular city are dioecious male and how the local pollen count might compare to similar environments that use both male and female.

Meanwhile, Ogren makes his living as a consultant to those wanting to plant gardens that reduce allergens. How fortunate for him that every few months a new article pops up featuring just him as a sole expert, talking about botanical sexism, with no actual science cited. So fortunate!

So do “male” plants cause seasonal allergies? Yep, but not nearly as much as plants with both male and female parts. The way to help the problem isn’t to plant more “female” plants, but to plant things that are pollinated by insects. You can spot those really easily — literally! They’re the plants with colorful flowers, which evolved to attract pollinators to them, meaning that they don’t have to blow a giant load of tree-men all over the neighborhood in the hope that the wind might carry some of it into a female flower.

Oh, and take global warming seriously. Warmer temperatures extend the time that plants blast their pollen into the air — back in April, researchers published a study in PNAS that found that since 1990, pollen season has grown by about 20 days, and to make things even worse pollen concentrations have risen by 20%. Oh and past research has found that air pollution can interact with pollen, causing it to explode into smaller particles that can work their way deeper into your lungs. So that’s fun.

Remember last week when I said that uncontrolled global warming can lead to the things that currently help us turning against us? Yeah, that’s…that’s actually already happening. Sorry. But at least now I have a video I can point to the next time a men’s rights activist claims I blame everything on sexism. Not this time!

Rebecca Watson

Rebecca is a writer, speaker, YouTube personality, and unrepentant science nerd. In addition to founding and continuing to run Skepchick, she hosts Quiz-o-Tron, a monthly science-themed quiz show and podcast that pits comedians against nerds. There is an asteroid named in her honor.

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