ROBERT SIEGEL, host:
If you are suffering from pollen in the air and if that suffering is as predictable as perennials, then you may be the indirect victim of sex discrimination. So says Thomas Ogren, who is among other things the creator and namesake of the Ogren Plant Allergy Scale, OPALS.
Mr. Ogren, if I understand this, the reason that there's so much pollen in the air is that there are so many male as opposed to female trees and plants around. Is that right?
Mr. THOMAS OGREN (Ogren Plant Allergy Scales): That's right, Robert. In urban landscapes, there's virtually no sexual diversity. There's a big preponderance of male trees and shrubs and a scarcity of females. And so for example, if I'm in a typical male city and I see a ash tree, which is one of the most common landscape trees, 99.9 times out of 100, it will be a male tree. And being a male tree, it'll produce pollen. And then a female Ash tree, for example, of course will shed seeds.
And so in horticulture, they made the swap years ago. This goes back 30, 40 years now to where in return for less litter, hence no seeds or fruits, they planted male versions. But they never thought about the pollen aspects. And so we now have pollen loads in urban areas that are much higher than they are out in the countryside. Out in the countryside, you basically have sexual diversity of plants.
SIEGEL: But once you're in the city, it's a man's world when it comes to trees.
Mr. OGREN: Yeah, yeah. I guess you could say that. But it's not necessarily a healthy place for a man or a woman.
SIEGEL: Well apart from the health effects on humans and the fact that this great preponderance of male trees, they're emitting the pollen, is it harmful to the population of trees? That is, do trees need sexual diversity to remain healthy and to procreate or we don't want these trees to procreate?
Mr. OGREN: No. They're almost all, what they call woody ornamentals in horticulture, they're almost all propagated now through asexual propagation, meaning through grafting, budding, air layering, tissue culture division or some other form that doesn't involve seed. But it is also harmful to the urban populations of birds and butterflies. For example, female trees and shrubs provide nectar and fruit for butterflies and birds.
SIEGEL: We're seeing the fruit, figuratively, alas not literally, we're seeing the fruit of decisions made 30 or 40 years ago. How long would it take for a large city to restore sexual diversity to its tree and plant population?
Mr. OGREN: The average urban street tree has a lifespan of only seven years. The reason is, is that many trees that are planted die young. Other trees are run over by drunk drivers and cars and ruined. Insects kill trees. And so there is a fairly rapid turnover. And so within a few years we start seeing a difference.
Also there's, most cities now have what are called tree committees and a tree committee makes a decision on whether you can remove a tree or not. And if they put in the allergy/asthma component into the potential removal of a tree, that would help accelerate the whole turnover to where we would have a less pollen-intensive urban landscape.
SIEGEL: Well, Mr. Ogren, that's fascinating. Thank you very much for talking with us today.
Mr. OGREN: Oh my pleasure talking to you.
SIEGEL: Tom Ogren, who spoke to us from Brazoria, Texas, today is the author of ALLERGY-FREE GARDENING and SAFE SEX IN THE GARDEN.
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