Pollen tube (plural pollen tubes) the tube that develops from the wall of a pollen grain and, in seed plants, provides a passage through which the male nuclei reach the embryo sac to effect fertilization.

Pollen Tube

A pollen tube is a slender, tubular structure that is formed by a pollen grain during the process of reproduction in plants. It plays a crucial role in the fertilization of plants, especially in angiosperms (flowering plants). The pollen tube is responsible for delivering the male gametes (sperm cells) to the female reproductive organs of the plant, thus enabling successful fertilization.

Formation of Pollen Tube:
The formation of a pollen tube begins when a pollen grain lands on the stigma of a flower. The stigma releases certain chemicals that stimulate the germination of the pollen grain. The pollen grain absorbs water and swells up, and a small opening called the germ pore is formed. Through this germ pore, the pollen tube starts emerging from the pollen grain.

Growth and Development:
The pollen tube grows by elongating its tip through a process called tip growth. The tip of the pollen tube is rich in vesicles, which contain various substances required for growth. These substances are released at the tip of the tube, allowing it to elongate. The tube grows through the style of the flower, which acts as a pathway for the pollen tube to reach the ovary.

Role in Fertilization:
The main function of the pollen tube is to transport the male gametes from the pollen grain to the ovary, where the female gametes (eggs) are located. The pollen tube penetrates the style, moves through the transmitting tissue, and enters the ovule. Once inside the ovule, the pollen tube releases the male gametes, which then fuse with the female gametes, resulting in fertilization.

Factors Affecting Pollen Tube Growth:
Several factors can influence the growth and development of pollen tubes. These include temperature, humidity, nutrients, and the presence of certain chemicals. For example, certain chemicals released by the female reproductive organs can attract the pollen tube and guide its growth towards the ovary.

In conclusion, the pollen tube is a vital structure in the reproductive process of plants. It enables the transfer of male gametes to the female reproductive organs, ensuring successful fertilization and subsequent seed formation. The growth and development of the pollen tube are influenced by various factors, and its formation and function are crucial for the survival and propagation of plant species.

It is a tube grows up from pollen grains