What Is the Process of Fertilization in Flowering Plants Where New Seeds Are Formed?

A variety of insects act as pollinators

Fertilization occurs in flowering plants when the male pollen or gametophyte, assisted by various agents, pollinates the ovum, a process that can occur within one flower or between the flowers of the same or different plants.

Pollen

Pollen developed and ready to fertilize.

Pollen is the male component of the fertilization process and is found on the anther. A grain of pollen contains two and occasionally three, gametophytes, which consist of the germ cell and the tube cell. The germ cell will divide by mitosis into two sperm cells, while the tube cell will grow into the pollen tube.

Pollination

A honey bee fertilizes a flower while feeding.

Pollination occurs when the male pollen are carried from the anther to the female stigma in the same flower, other flowers on the same plant or flowers on other plants. Pollinators or carriers include birds, bats, insects, humans and the wind. It is thought that the flower may dictate the pollinator by its color and size, brighter, larger flowers being attractants to insects while smaller, insignificant flowers have wind-borne pollen and no need of insects.

Fertilization

Hummingbirds are diligent pollinators of flowers in their search for nectar.

When the pollen reaches the pistil or gynoecium, consisting of the stigma, style, ovary and receptacle, its tube cell attaches to the receptive stigma and develops into a pollen tube through which two sperm cells, released from the male germ cell, travel to reach the ovum. At the same time he male cell is growing, the female cell in the ovule within the ovary at the base of the pistil is developing.

The male sperm move through the ovule wall and while one fuses with the egg, the second develops into the endosperm tissue, which will nourish the developing zygote or seed.

References

• University of Manitoba; The Life Cycle of an Angiosperm; Rick Shaw; October 1995
• Estrella Mountain Community College; Flowering Plant Reproduction; M.J. Farabee; 1992