What types of pollen will trigger allergy symptoms?

Trees, grass, weeds: Pollen are fertilizing grains produced by plants for propagation. Some plants use the wind to help in pollination producing massive quantities of pollen that become airborne; these include trees, grasses, and weeds. If you are prone to allergies, these plants can cause symptoms during certain seasons. Plants that make pretty, fragrant flowers attract insects for propagation & don't cause allergies.

Pollen allergies: Trees, grasses, weeds, molds, danders (cat, dog, horse, etc), dust and dust mites, agriculture (corn pollen, oat pollen, etc).