By Elizabeth Crews
After years of his wife suffering with severe allergies and asthma, Thomas Leo Ogren was determined to find a solution to suppress her symptoms. What began as a singular journey to help his wife transformed into decades of research that established him as an allergy expert and the author of the most comprehensive botanical allergy books in existence. He realized that the number of individuals with allergies was increasing exponentially, although one of the causes for this suffering is simple: botanical sexism.
Male v. Female Plants in Landscaping
In The Allergy-Fighting Garden, Ogren discusses the reproduction of plants and trees, focusing specifically on those that are dioecious. These plants have distinct male or female reproductive systems. The males produce pollen, which travels to the females to create seeds and fruit.
Male plants are most often used by cities and homeowners because they do not produce seeds or fruit like the females. Because of this, females are considered to be high-maintenance and require more upkeep, whereas the males are considered easier to manage. This practice is called botanical sexism.
Issues with Botanical Sexism
Ogren maintains that the best treatment for allergies is avoidance. There are medications and inhalers we can use when we experience reactions; however, he states that intentional planting is the key to decreasing reactions. The males are designed to create pollen and they will continue to send the highly-adhesive particles into the air. If there are no females there to accept the pollen, it seeks another tall surface to adhere to: often people . Breathing in these sticky particles causes trouble for those with asthma, allergies, and compromised respiratory systems. While planting male trees is often perceived as lower maintenance, the lowest-maintenance option is actually to plant females alone: they do not produce the same high rates of irritants, and without pollination they cannot produce messy seeds and fruit.
That being said, there are benefits to planting males and females together for sexual reproduction. The singular incorporation of male plants and trees has decreased biodiversity, which increases vulnerability to diseases like the Dutch Elm Disease. It was introduced in 1930s and laid waste to male American elm trees, which were commonly used for their shade. Their close proximity allowed the disease to easily spread from one elm to the next until they were all but completely wiped out. The impressive American elm population never recovered from that devastation.
Governments have also planted male clonal trees. Groups of asexual clonal trees or plants are called colonies, and they are genetically identical and connected by the same root system. As a colony asexually reproduces, single cells multiply to create more, and mutations can occur at a higher rate than during sexual reproduction.
In a study of famous clonal aspen trees nicknamed Pando, botanists have noted that the trees’ sexual fitness decreases with age, meaning the trees do not reproduce as rapidly. If dangerous mutations occur and are asexually produced rapidly, the organism runs the risk of continuing to produce mutated cells, which make them even more vulnerable to diseases like the Dutch Elm Disease.
OPALS: The Solution
To help people plan the most allergy-friendly gardens and landscapes, Ogren developed the OPALS system. The acronym stands for the Ogren Plant Allergy Scale and it details the least to most allergenic plants in an easy-to-read scale of 1-10. It is currently the most comprehensive guide and it was met with such high esteem that branches of the USDA have incorporated it into their landscaping. In addition to landscaping with low-OPALS-rated plants, planting females to receive male pollen (especially in public spaces) will dramatically decrease human exposure to allergens. This book and the rest of Ogren’s work have made it possible to easily create a garden that is allergy friendly.
To learn more about how you can apply this to your own home or homestead, we recommend purchasing Ogren’s book! Using this link to Amazon doesn’t cost you anything, but we are paid a percentage of Amazon’s profit from your purchase!