Botanical Sexism Cultivates Home-Grown Allergies

These new male trees were soon joined by clonal male plants from a great many other dioecious tree species (having distinct males and females) such as willows, poplars, aspens, ash, silver maples, pistache, mulberry, pepper tree, etc. It took a number of years for these new trees to mature enough to start to bloom, but eventually they did and with them came more city pollen and the “epidemic of allergy and asthma.” But what if that same tree is a clonal male, and each year it sheds vast amounts of airborne pollen?

Source: blogs.scientificamerican.com