Seeds are produced by plants during their growth phase. They are significantly smaller than the plants that produce them. The seeds are planted to create new plants of the same species. All types of seeds, no matter what plant produced them, have the same basic seed structure.
All seeds have an outer covering, called the seed coat. All seed coats protect the seeds' interiors from drying out. Seed coats vary from plant to plant. Some seed coats are thin and easily penetrated (like a pea or bean), while others are thick and strong (like peach pits).
Endosperm is a seed's temporary food supply. The seed uses endosperm for energy to develop. Seeds need endosperm to break open and force seedlings through the seed's opening.
Cotyledons are rudimentary leaves that absorb the energy of the endosperm. These cotyledons unfurl and break through the seed and soil surface. Cotyledons develop into the first leaves on a growing, developing plant.
Monocotic seeds contain only one cotyledon within the seed. Monocots develop into single-leafed structures. An example of a plant that grows from a monocot seed is grass.
Dicotic seeds contain a pair of cotyledons inside the seed. When the plant structure develops, there are a pair of leaves, with one being on each side of the stem. An example of a plant that develops from a dicotic seed is a tomato plant.