FERTILISATION

The fusion of a male gamete from pollen with a female gamete in the ovule to produce the embryo. `

Fertilisation is the process where a male nucleus (gamete cell containing a single set of chromosomes “Haploid”) contained in a grain of pollen, joins with the female nucleus (gamete) contained in an ovule in the ovary. This union forms a cell containing the 2 sets of chromosomes (called a Zygote “Diploid” cell) which will result in a single seed. The pollen settles on the stigma. From the pollen grain a tube grows down the style, controlled by the tube cell nucleus, to the ovary entering via the micropile and into an ovule. Travelling behind the tube nuclei is a generative cell. Before entering the ovary this divides into 2 haploid sperm cells, each with a single set of chromosomes. On entering the ovary one cell fuses with the egg cell which forms the new diploid cell and the seed embryo. The second fuses with the polar nuclei and forms the seed food source (cotyledons) of the seed.