Seeds are made within the ovaries of some species of plants. Not all plants have the ability to produce seeds. Only those in the divisions Cycadophyta, Ginkgophyta, Gnetophyta, Coniferophyta and Anthophyta use seeds for reproduction. They are generated from the ovule of the mother plant and the pollen grain of the father plant.
A seed, which is generated in the ovule of the female plant, consists of several parts. The embryo is the structure that later grows into a mature plant. It contains one set of chromosomes from the mother plant and a second set from the father. There are four main parts of the embryo. The cotyledon is a seed leaf that stores food, the plumule and hypocotyle are the embryo plant's stem and shoot, and the radicle later develops into the plant's root. In addition to the embryo, the seed contains endosperm, which contains two sets of chromosomes from the mother and one from the father. The endosperm provides the plant with a food source as it germinates into a tiny plant. Both the embryo and the endosperm are encapsulated in a seed coat, which develops from the embryo sack of the mother plant's tissue. The seed coat is a tough, protective layer than prevents damage to the embryo and endosperm.