We planted the pollen problem

May 2, 2019 11:56 AM

Hit full-force by spring allergies? In many cities, the bias against female trees, which bear potentially messy fruit in summer and fall, has led to exclusively planting male trees — the kind that release pollen. Which makes many people sneeze. A guest blog for Scientific American by horticulturist Thomas Leo Ogren lays out how and why this came to be.

Ogren, who created a scale to rate how allergenic plants are, has written several books about reducing allergies in the home garden. He also works with public health departments in California (PDF link) to encourage planting less-allergenic plants to reduce asthma rates and improve air quality.

The idea is catching on: Building a Low-Allergen Plant Palette (blog post from the American Society of Landscape Architects)

Bonus link: Do you live in one of the allergy capitals in the United States?

posted by purpleclover (21 comments total)

Goddamit. Is *this* why May and June are miserable for me every year? Because of city policy?
posted by Mogur at 12:04 PM on May 2, 2019 [3 favorites]

Can't blame city policy on the allergies around here in Asheville, NC. We are surrounded by beautiful tree-covered mountains and every spring it rains yellow dust, sometimes so bad that it bothers me, and I don't even have allergies!
posted by rikschell at 12:20 PM on May 2, 2019 [2 favorites]

I guess I’d have to buy the guy’s book to see the full listing of plants on the proprietary scale that he named after himself.
posted by Huffy Puffy at 12:28 PM on May 2, 2019 [1 favorite]

The pollen has been particularly bad this year, but I would caution everyone to take seriously the downside of fruit-bearing trees as someone living in a city with a large population of gingko trees.
posted by Copronymus at 12:34 PM on May 2, 2019 [3 favorites]

While city policies and marketing of "litter free" trees undoubtedly plays a role, it's not the only factor making things worse-- rising CO2 and rising temperatures also contribute to allergen production and longer allergy seasons: A Changing Climate Worsens Allergy Symptoms
posted by shenderson at 12:34 PM on May 2, 2019 [7 favorites]

Well, this seems relevant.
posted by Naberius at 12:43 PM on May 2, 2019

"Oooh" the kids say, "let's go out and make pollen angels" when they see a dusting of yellow on the ground. Ahh yeah pollen season.
posted by The_Vegetables at 1:04 PM on May 2, 2019 [2 favorites]

This column stinks to high heaven. Let's start with the paragraph that caught my attention:

Female trees, even if they make seeds or pods, have much to offer us. A large female tree may easily have millions of individual flowers on her as she blooms. These tiny flowers are slightly sticky and feathery, and they produce a small negative electrical impulse. Pollen from male trees tumbles about in the air and picks up a positive electrical impulse. When you have negative and positive the result is mutual attraction. The pollen grains do not just get to the female trees by accident; rather they are drawn there by this mutual attraction.

I'm sure the opposite charges of pollen and flowers helps pollination somewhat, but if female trees were sucking up pollen like a vacuum entirely due to static electricity, we could achieve the same effect for a lot cheaper with a few well-placed Van de Graaff generators.

[Absorbed toxins] are now in and are part of the tree itself... what if that same tree is a clonal male, and each year it sheds vast amounts of airborne pollen?

"What if", indeed? Do these toxins actually appear in tree pollen? It sounds like it would be pretty easy to gather a bunch of pollen, test it in the lab, and get a paper published. But this column cites no such paper, instead opting for dire warnings about how YOUR CHILDREN ARE IN DANGER:

Consider this: small children play hard and while playing they breathe in rapidly and are exposed to two to three times more pollutants in the air than adults are. It is also worth noting that schoolyards are often the places with the most allergenic trees.

But there are a few problems with the article at that link. First, it was written by a law professor and published in a law review journal, not a biology or medical journal. Second, this article thanks Thomas Ogren, the column's author, by name, and extensively cites his book throughout. Finally, the specific claim that the column is trying to buttress by linking to this article isn't supported by any external source!

And now here's the really shameless bit:

Children are not the only ones at risk, however. Women who have airborne allergies have been found to be at increased risk from leukemia, ovarian cancer and breast cancer, according to a 2010 study published in Cell Biology.

Let's set aside the fact that this claim says nothing about whether pollen exposure is connected to cancer, but only airborne allergies. I wasn't able to verify the claim at all. Not only is this link conveniently paywalled so normal people can't verify it, but it doesn't even link to the journal this article was supposedly published in, but instead to Medscape, which is essentially a medical news aggregator. Which is a shame, because I did a lot of searching, but I couldn't find any article in 2010 connecting allergies and cancer in any journal with "Cell Biology" in the name. But I'm sure there's no way that this "essentially a horticultural epidemiologist" who didn't get a PhD could be making this up, right? It is truly depressing that this is the kind of crap that Scientific American puts their name on these days.
posted by J.K. Seazer at 1:36 PM on May 2, 2019 [11 favorites]

It looks that this is the paper in question, though the link is only with hematologic malignancies, not other types of cancer. I agree that the way the column is written is way too much on the self-promotion side.
posted by elgilito at 2:55 PM on May 2, 2019 [1 favorite]

YET AGAIN IT’S THE MEN
posted by schadenfrau at 3:33 PM on May 2, 2019 [2 favorites]

Beijing had a very overt problem with sex-selective tree planting and the consequent pollen, which manifests as the “spring snow”. An area where I used to live had been heavily planted and it really did feel like wading through ankle-deep snow each spring. Article from That’s Beijing - apparently the authorities are planning to deal with the problem, (which will likely involve uprooting all the trees with no plan to replace them, if my experience of the city planning authorities are representative).
posted by chappell, ambrose at 3:42 PM on May 2, 2019 [1 favorite]

Hm.

So there's a conversation to be had about our choices in what ornamental trees we plant. For instance, there's a female ginkgo tree outside the dining hall on my campus, which is delightful when it drops its vomit-scented seeds on the ground and everyone tracks them in.

And there's a nugget of truth in the idea that pollen and flowers have an electrical charge (and it seems like bees may get some useful information out of reading these electric fields).

But, this is a charge like how you get a bunch of dust stuck to something when there's static. Planting more flowers isn't going to somehow suck allergens out of the air; wind pollination really, really is about pollen getting carried everywhere in the breeze, and hopefully some of it lands in the right place.

I have never heard anything at all about toxin accumulation in pollen.
posted by pemberkins at 3:56 PM on May 2, 2019

As someone who takes Allegra every morning starting in March, I understand the appeal of reducing pollen. But I also currently live in an apartment with an (ornamental) pear tree in the back yard, and last year's bumper crop had us picking up gallons of pears daily. If we left them for even for a few days they'd start rotting, stinking, and attracting rats and wasps. The squirrels would take one or two bites of the ones still on the tree, and then drop them. Often they'd drop the little pieces they'd bitten off, too, which were nearly impossible to pick up. I will NEVER again live somewhere with a fruit tree.

And yeah, I pass a gingko tree on the way to the train every day and when that thing drops its fruit, the smell is just awful.
posted by misskaz at 4:36 PM on May 2, 2019

It's almost like literally every time a public municipality tries to save money to satisfy greedy selfish rich and upper-middle class people who don't want to pay taxes to support the society that enabled them to get that rich, it causes larger problems for society that definitely isn't worth the "benefit"! Huh!
posted by Caduceus at 4:37 PM on May 2, 2019

Easy there, Robespierre. They're just trees.
posted by TrialByMedia at 6:24 AM on May 3, 2019 [1 favorite]

Can't blame city policy on the allergies around here in Asheville, NC. We are surrounded by beautiful tree-covered mountains and every spring it rains yellow dust, sometimes so bad that it bothers me, and I don't even have allergies!

The annoying yellow shit you can see isn't the allergenic stuff. It's too big to be absorbed by the body. It does make everything look gross, though.
posted by Fleebnork at 6:45 AM on May 3, 2019

Fuck the plantriarchy!
posted by fiercecupcake at 7:19 AM on May 3, 2019 [2 favorites]

The annoying yellow shit you can see isn't the allergenic stuff.
Citation needed? I'm hella allergic to evergreen pollen and a lot of them do some nice big yellow clumps.
posted by aspersioncast at 11:02 AM on May 3, 2019 [1 favorite]

I'm sure the opposite charges of pollen and flowers helps pollination somewhat, but if female trees were sucking up pollen like a vacuum entirely due to static electricity, we could achieve the same effect for a lot cheaper with a few well-placed Van de Graaff generators.

Ah, brings back memory of my childhood, growing up on a Van de Graff generator-lined street. The air was clear of pollen but I could never get my hair combed properly.
posted by Merus at 2:41 PM on May 4, 2019 [2 favorites]

Some of the hairstyles of the 1960’s and 70’s make so much more sense now.
posted by Huffy Puffy at 3:16 PM on May 4, 2019

Citation needed? I'm hella allergic to evergreen pollen and a lot of them do some nice big yellow clumps.

Allergist: Don't blame pine pollen

"People attribute their allergies to pine pollen because it's visible, but it's actually too large to cause allergies," Dr. Maya Jerath of the University of North Carolina at Chapel Hill School of Medicine says in a statement. "It's the other trees blooming at the same time like maple, oak and birch."

posted by Fleebnork at 5:57 AM on May 10, 2019