Of the 650 trees native to the U.S., the pollens of about 100 are allergens. Some of the most common culprits are: Alder, Ash, Beech, Birch, Chestnut, Cypress, Japanese Cedar, Western Red Cedar, Elm, Hazel, Heath, Hickory, Maple, Myrtle, Mulberry, Oak, Olive, Pine, Plane, Poplar, Ti, Wattle, Walnut, and Willow.

During tree season, keep windows closed tightly and use the air conditioner rather than window or attic fans. Most people are allergic to a single species, but people may be allergic to several members of certain families, particularly these:

When planting trees in your yard, try choosing varieties that don't cause allergies. Some candidates are: catalpa, crape myrtle, dogwood, fig, fir, palm, pear, plum, redbud and redwood trees.