Is Sexism Making Our Allergies Worse?

As the allergy season was in full swing, a TikTok by Ellie Botoman was going viral for claiming that cities have been amplifying the effects of allergies by planting primarily male trees. The video ends with the text: “You’re sneezing and congested all day [because] of botanical sexism.” Predictably, what appears to be as a simple fun-fact-of-the-day on the internet, turns out to be a much more controversial issue with years worth of scientific discourse behind it.

With pollen counts continually rising and allergenic tree pollen being one of the biggest contributors to hay fever, people have been relying on antihistamines to combat their symptoms. But American horticulturist Tom Ogren argues that there is a simple, preventative measure: a bigger mix of female and male trees in urban landscapes. After noticing the thick, yellow pollen covering the ground in the streets of Sacramento, California, Ogren found that the trees along the street were cultivated males of the deodar cedar. Having moved to California, Ogren’s wife developed terrible allergies, motivating him to continue researching the local flora. His observation of male tree species dominating his neighbourhood led him to coin the term “botanical sexism”, a concept describing landscapers and city planners favouring planting male trees over female ones of specific species, including but not limited to willows, fern pines and silver maples. In his eyes, male trees are a capitalist scam.

But why would male trees be superior to female trees in a city setting? In support of his ideas, Ogren and sympathizers refer to the 1949 USDA Yearbook of Agriculture, which recommends only the selection of male trees for easier maintenance, bypassing the nuisance of cleaning litter in the form of flowers and fruit. Ogren’s manifesto calls for increased sexual diversity in city flora, where female trees can trap and remove excess pollen from the air. He also recommends the implementation of a self-created rating scale to measure pollen levels. Overall, by avoiding planting pollen-heavy trees and focusing on the scarcity of female trees, we can stop the “allergy epidemic” plaguing cities.

Although there is some merit to Ogren’s claims, many scientists are critical of his theory. Another viral Twitter thread by crop scientist Sarah Taber discredited the theory altogether. According to her, a key issue at the core of botanical sexism is that most tree species are not distinctly male or distinctly female, so by definition planting only males would be impossible. An estimated 5% of trees are dioecious, meaning that a vast majority of single trees can have both male and female reproductive organs (known as monoecious) – it’s rarely an either or scenario, as presented by Ogren. An even more interesting concern was raised regarding Ogren’s course material. The passage he references in the Department of Agriculture’s Yearbook refers to a specific tree species – cottonwoods. The recommendation for male trees is to prevent seeds from clogging sewers, and their weak wood from ensuing chaos during storms. Not only is this botanical bias limited mostly to North America, it also only applies to a handful of species, and is probably not as widespread an issue as presented by the theory’s creator.

Although Ogren and Taber hold opposing opinions on the issue, the truth is likely more nuanced. Unfortunately, there is little independent data on the prevalence of male versus female trees in urban settings. What little information there is actually traces back mostly to Ogren’s own allergy assessment of Canadian cities. But given that tree species in city areas are not representative of the natural flora in surrounding areas, there is a chance that there might be some imbalances. Furthermore, although trees can be cultivated to drop their female traits, like fruit, some argue this is purely for aesthetic reasons – like wanting a specific colour of leaves.

Assuming this is a real issue, how do we implement a solution? An allergy rating system sounds appealing, but would be hard to implement. With scarce information on the prevalence of distinct plant species and the number of people who are allergic to them, generating such specific data is incredibly difficult considering the large amount of data, inaccurate allergenic tests or allergens changing over time. Similarly, cutting down every male tree and replacing it with a female counterpart is a task of biblical proportions. A more achievable proposal is increasing the tree diversity of existing populations, with a focus on insect-pollinated trees, rather than wind-pollination, which release less pollen. While Ogren and his supporters demand pollen-free cities and the prevention of the allergy epidemic as a basic human right, the only way to achieve this goal is through collaboration between public health and allergy experts with urban planners and landscapers.

Not only have the core principles of this phenomenon been criticized, but many also highlight the problematic nomenclature. While Ogren stands by his opinion that this botanical issue is an example of sexism, it seems that the attention-grabbing name alone is driving much of the interest. Putting all the scientific insecurities and limitations aside, it could be argued that Ogren is trying to make his theory appear more tangible by drawing on an existing cultural issue. Social media is propelling this perceived slight against city dwellers with its tendency to portray everything as black-or-white, with little to no consideration for nuance.

Flaws notwithstanding, Ogren’s observation of worsening allergies appear somewhat justified. However, experts warn that there are other important (measurable) factors that are likely to increase sensitization to pollen, like climate change. Global warming, increased carbon dioxide levels and longer pollen season have been shown to increase pollen counts, with air pollution shattering pollen into thousands of smaller particles that are easier to breathe in and irritate our respiratory system.

So can we really blame sexism, that pervades every aspect of our life, for our allergies too? The answer is unfortunately more complicated than any curt TikTok can sufficiently tell us.