What Are Pollen Grains?

Gametes

• A gamete is a plant cell similar to egg and sperm cells in mammals. Gamete cells grow in to pollen grains during the reproductive cycle of a particular flowering or fruit bearing plant. The pollen grain contains the DNA necessary for the plant to reproduce. The cells are so small that they are measured in microns, like microscopic life. A micron is defined as 1-millionth of a meter, or one 1-thousandth of a centimeter.

What's Inside

• A pollen grain has a tough wall. There at least two layers to any pollen grain. The inner layer is defined as in the intine. The inner portion contains the cytoplasm extine is the name for the external layer. The extine contains a substance that protects it from decay. Because of this lack of decay and the extreme smallness of pollen, when it is in the air, you can breathe it in, causing "hay fever" symptoms.

Reason for Being

• A pollen grain exists to enable a plant to produce its fruit or flowers. Pollen grains are contained on the stamen or male part of a plant. Pollen grains move in the air from the stamen to the pistil or female part of the plant. In a plants reproduction season, usually the spring, millions of pollen grains are released into the air by wind. Some land on the pistil of a plant; some linger in the air.

Pollinsation

• Some plants self-pollinate. These plants have larger stalks on their stamen. The pollen grains fall within the plant, and the male cells pollinate the female cells to reproduce. Other plants require the assistance of insects like bees. Bees will take the pollen off of one plant and deposit it on another. This is called cross-pollination. Both of these activities enable plants to carry on their life cycle from gamete to fruit-bearing plant. The fruit of the plant often contains seeds that can grow in to mature copies of the same plant.