The three parts of a seed are the embryo, the endosperm and the seed coat. The embryo is a miniature form of the plant that is fed by the nutrition contained in the endosperm. The embryo is protected from the external environment by the seed coat.
The embryo grows inside the seed until it is able to break through the surface with its initial leaves and roots. It feeds off the carbohydrates, proteins and fats found in the tissues of the endosperm. It is safely enclosed in the seed coat, which keeps disease, insects and water away from the vulnerable young plant until it is ready for germination.