Pollen

Pollen is a fine to coarse powdery substance comprising pollen grains which are male microgametophytes of seed plants, which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophytes during the process of their movement from the stamens to the pistil of flowering plants, or from the male cone to the female cone of coniferous plants.

Structure and formation

Pollen grains are encased in two protective walls. The inner wall is called the intine and the outer wall is called the exine. The formation of pollen occurs in the anther, a male reproductive organ of the flower. The pollen is transferred from the anther to the stigma of the same or a different flower through a process known as pollination.

Types of Pollen

There are two types of pollen: entomophilous, which is transferred by insects, and anemophilous, which is transferred by the wind. Entomophilous pollen is usually larger because it has to stick to the insect that transports it. Anemophilous pollen is smaller and lighter, which allows it to be carried by the wind.

Role in Allergies

Pollen is a common allergen. Many people have adverse immune responses when they breathe in pollen. This can lead to conditions such as hay fever, asthma, and conjunctivitis.

Role in Agriculture and Horticulture

In agriculture and horticulture, pollen can be used for breeding. For example, in fruit breeding, pollen from one variety of apple is used to pollinate another variety of apple to create a new breed of apple.

See Also

• Pollen tube
• Pollen source
• Pollen allergy
• Pollen calendar

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