Pollen grains in country air, illustration. Pollen grains (which are smaller than shown here) have different sizes and shapes, depending on which flower has produced them. These pollen grains are being dispersed on the wind. Each pollen grain contains a male gamete (reproductive cell) that is intended to fertilise the ovule or egg (female gamete) of another plant of that species, forming the seed for a new plant. High pollen levels can trigger allergic reactions such as hay fever. The allergic reaction inflames the membranes of the eyes and nose, causing watering eyes and sneezing.