Most trees release their pollen in the late winter and early spring. In the Southeastern U.S., tree pollen season can begin as early as January. Contrary to popular belief, it is typically not the trees with large, colorful flowers that cause allergy, but more often those trees with smaller more inconspicuous flowers. Some of these allergy-causing trees include:
Ash, Aspen, Beech, Birch, Box Elder and other maples, Cedar, Cottonwood, Elm, Mulberry, Oak, and Willow.