“If people even know that there are male and female trees, they certainly aren’t thinking about the impact on pollen and allergies,” Clow said. “We love to talk about the sort of botanical imbalance in male and female trees and the way that’s been perpetuated over time without real awareness around it. We felt this was something just truly powerful to unearth, and found a really wonderful way to do that with the DiverisTree Project.”
Beyond the female trees that get distributed, the campaign should help raise awareness about the issue among homeowners and nurseries, where trees today often aren’t labeled as male and female, Clow said.
“Claritin is on a mission to help reduce pollen levels and restore botanical balance,” said Catherine Vennat, VP and general manager for upper respiratory at Bayer, in a statement. “Through female tree plantings in cities across the country, we’re aiming to help communities one tree at a time and are committed to research within the field of plant science, all with the goal of having everyone enjoy the outdoors every day.”
Claritin also is hosting female tree-planting events in two cities ranked by the Asthma and Allergy Foundation of America as some of the hardest places to live with allergies—New Orleans and Richmond, Virginia. And the brand is conducting a study to be released on April 7 in partnership with Dan Katz, senior research fellow at the School of Integrative Plant Science at Cornell University, on the potential for planting low-pollen trees, including female trees, to reduce airborne pollen concentrations in New York City over the next 50 years.
Beyond the pollen issue, tree gender is complicated, in part because trees, particularly within some species of maple, sometimes spontaneously change genders. Only about 20% of trees in the Eastern U.S. are dioecious, where entire trees are strictly male or female. Most are co-sexual, with flowers that have both male and female parts fully functioning—or polygamous, with a mix of male and female flowers on the same tree.