Seeds

Seeds are a product of sexual reproduction when pollen fertilises an egg.

Fertilisation can only take place when pollen is alive and compatible and the stigma is receptive.

When the stigma is receptive it produces a sticky solution which ensures the pollen sticks to it. This sticky solution also provides energy for the pollen to germinate.

When pollen lands on the stigma it germinates and divides into two cells. One cell rapidly promotes a pollen tube growth through the style and into the ovule where the egg resides.

The other pollen cell divides and becomes two sperm, which travel down the pollen tube to the awaiting egg for immediate fertilisation.

At this stage a zygote is formed as one of the two sperms fertilises the egg. The second sperm unites with another cell in the ovule and produces an endosperm, a food storage unit which will provide food as the zygote develops into an embryo.

Fully developed seeds consist of a: