The Mulberry tree (also know as Fruitless Mulberry or White Mulberry) is often cited in stories relating how Arizona went from a favored destination for allergy sufferers to one of the worst places to live if you have allergies or asthma. New Arizona residents moving in from the South and East preferred the stately, large-leaved, shade trees they left behind to the local desert varieties and so thousands of Mulberry, Olive, and Ash trees were planted throughout the valley. Spring tree pollen levels in Phoenix were fairly low 40-50 years ago but over the past 30 years, pollen levels in Phoenix have skyrocketed and along with it, the Phoenix allergy-misery level. To stem the flood, Phoenix passed the Airborne Pollen Ordinance which restricted the planting of male Mulberry and Olive trees. As a result, there are few Mulberry trees in the newer communities of Phoenix such as the Foothills in Ahwatukee, although there are enough established trees in the valley to supply the rest of the area with pollen for many years ago come.
Pollination: February through April