Q.What is the function of the two male gametes produced by each pollen grain in angiosperms?

Function of the Two Male Gametes in Angiosperms

Each pollen grain in angiosperms produces two male gametes (sperm cells) through mitotic division of the generative cell. These two gametes have distinct, complementary roles in the unique process of double fertilization that defines flowering plants.

The two male gametes function as follows:

• First male gamete: Fuses with the egg cell in the embryo sac to form the diploid zygote, which develops into the embryo of the seed.

• Second male gamete: Fuses with the two polar nuclei (or the secondary nucleus formed by their fusion) in the central cell to form the triploid primary endosperm nucleus, which develops into the endosperm that nourishes the developing embryo. …

When a pollen grain lands on a compatible stigma and germinates, it produces a pollen tube that grows down through the style toward the ovule. Inside this tube, the generative cell divides to produce two male gametes (also called sperm cells). These are not motile like animal sperm; they are simply non-motile nuclei carried passively by the pollen tube. The question is: why two, and what does each one do?

The answer lies in one of the most distinctive features of angiosperm reproduction — double fertilization. This process, unique to flowering plants, involves both male gametes in separate fusion events, each with a different outcome.

The fate of the two male gametes

Once the pollen tube enters the embryo sac through the micropyle, it releases both male gametes into the synergid cell. From there, the two gametes move toward different targets:

• First male gamete: This one fuses with the egg cell (located at the micropylar end of the embryo sac). The fusion produces a diploid zygote, which will develop into the embryo — the future plant. This is syngamy, the true fertilization event that ensures genetic continuity.

• Second male gamete: This one moves toward the central cell, where it fuses with the two polar nuclei (or the secondary nucleus, if the polar nuclei have already fused). This triple fusion produces a triploid primary endosperm nucleus, which divides repeatedly to form the endosperm — the nutritive tissue that nourishes the developing embryo.

Why this division of labor matters …