Pollen: Small, light, dry protein particles from trees, grasses, flowers, and weeds that may be spread by the wind. Pollen particles are usually the male sex cells of a plant, and they are smaller than the tip of a pin. Pollen is a potent stimulator of allergic responses. It lodges in the mucous membranes that line the nose and in other parts of the respiratory tract, causing irritation and histamine reactions.
Reviewed on 12/27/2018