What is the process of fertilization in plants?

Fertilisation in plants involves the fusion of male and female gametes, specifically the pollen grain and the ovule.

Fertilisation in plants is a complex process that begins with pollination, the transfer of pollen from the anther (male part) of a flower to the stigma (female part) of either the same flower or another flower. This can occur through various means such as wind, water, or animal vectors. The pollen grain, which contains the male gametes, then germinates on the stigma and grows a pollen tube down the style towards the ovary, which contains the female gametes or ovules.

The pollen tube's growth is guided by chemical signals from the ovule. Once the pollen tube reaches the ovule, it penetrates through the micropyle, a tiny hole in the ovule. The male gametes then travel down the pollen tube and into the ovule. This is where the actual process of fertilisation takes place.

There are two types of fertilisation in plants: self-fertilisation and cross-fertilisation. Self-fertilisation occurs when the pollen from the anther of a flower fertilises the ovule in the same flower. This process ensures the continuation of a plant's genetic material, but it does not promote genetic diversity. On the other hand, cross-fertilisation involves the fusion of male and female gametes from different flowers. This process promotes genetic diversity, which can lead to more robust and adaptable plant populations.

In angiosperms, or flowering plants, a unique double fertilisation process occurs. One male gamete fuses with the egg cell to form the zygote, which will develop into the embryo. The other male gamete fuses with two polar nuclei to form the endosperm, a nutrient-rich tissue that nourishes the developing embryo. This double fertilisation process is a distinctive feature of angiosperms and is crucial for their reproductive success.

In summary, fertilisation in plants is a complex process involving the transfer of pollen, the growth of a pollen tube, and the fusion of male and female gametes. This process is vital for the reproduction and survival of plant species.