About 20 years ago, horticulturist and author Thomas Ogren became interested in allergy-free gardening because his wife suffered from allergies and asthma. He has since discovered that many “dioecious male” trees trigger severe allergies (most people don’t realize that some plants are male, some are female, and many are bisexual). Pollen is the main culprit.
Ogren suggests that the allergy problem is increasing because male trees, which do not produce fruit, seeds, messy flowers or old seedpods, are being planted by the millions.
I’m going to have to revise my old credo: “If it’s got tires or dioecious male parts, it’s gonna give you trouble…”