The Anatomy of a Bean Seed

Bean plants sprout pods that contain seeds. Some pods, like those of green beans, are edible.

Simply put, beans are seeds. The small nuggets you know as lima beans, soybeans and other varieties are actually the seeds of those bean plants. Bean plants produce pods that contain several individual seeds inside. If you soak some beans overnight, you can examine them to see their different parts.

Seed Coat

The seed coat is the skin covering the seed and protecting its inner parts.

Micropyles

If you look at the seed coat closely, perhaps under a magnifying glass or microscope, you can see pores that allow the seed to absorb water. These pores are called micropyles.

Hilum

When looking at a bean seed with the seed coat still on, you'll notice a small scar on the skin. This is the hilum, where the seed was connected to the pod it grew in.

Cotyledon

Once you remove the seed coat from a bean seed, you're looking at the cotyledon. This part of the seed is food for the tiny plant the seed also contains, allowing it to survive until the seed is planted and can bring in nutrients from water and soil. Bean seeds are called dicotyledon, or dicot for short, because they contain two cotyledons to feed the plant inside.

Embryo

When you carefully split open a bean seed, you'll find the embryo: the tiny developing plant inside the seed. It will be surrounded by the cotyledon and located where the hilum was on the seed coat.

References

• Purdue University Horticulture: Senior Study - Vegetables
• GrowingYourFuture.com: Ag in the Classroom - The Anatomy of a Bean Seed