Seeds and Seed Germination

Seed Structure

Keep in mind that the ovule in the ovary is what becomes the seed. The integument of the ovule becomes the seed coat. Inside the integument of the ovule was the embryo sac. The antipodals and synergids senesce and disintegrate. The central cell united with one sperm cell to make endosperm...a nutritive tissue that accumulates starch, protein, and fats to provide for the growth of the embryo. The egg cell of the embryo sac united with the other sperm cell to make a zygote. The zygote grows and becomes a true embryo inside the integument.
We will recall that the seed developing in the carpel produces hormones that make the carpel develop into a fruit. The mother plant also produces abscisic acid to make the embryo inside the seed become dormant
When you have a Dormant Embryo, a Storage Tissue, and a Seed Coat, then you have a SEED. In some seeds, the endosperm is retained as the storage tissue. In other seeds the endosperm is more or less used up to put storage chemicals into the embryo itself (commonly in the cotyledons). Below are diagrams and a photo of some seeds.

This first example above, is a longitudinal section through a Capsella seed. You may observe several cell layers of seed coat (integument) on the outside. In the interior is an embryo. There is a root apex, a radicle that transitions into a hypocotyl terminating at the attachment node for two cotyledons between which we can see the shoot apex. The embryo may be bent, but it has all the parts of a typical embryo. Having two cotyledons means that Capsella is a dicot plant. Between the embryo and the seed coat is a layer of endosperm remaining; some is found between the radicle and the two bent cotyledons; more is found at the lower end of the seed.
The structure of dicot and monocot seeds is illustrated below. Obviously the dicot will have two