Beans are actually a common name for the seeds from plants of the Fabaceae family. These seeds are very popular as a food and as feed for livestock. Beans are full of protein and are easily grown in many conditions. The structure of a bean seed is common among many varieties.
The Seed Coat
The seed coat (testa) is the outer layer of the seed that protects it from damage from insects and disease. On the seed coat is also the micropyle, a small, porous area of the seed coat that allows water into the seed for germination during the growing period. The hilum, another part of the seed coat, is a small scar where the seed was previously attached to the plant stalk.
The embryo of the seed is inside of the seed coat. The embryo is the developing plant on the inside of the seed. Once water enters the plant, the embryo begins to germinate and sprout from the shell of the plant.
Until the seed gets sustenance from nutrients in the soil, and from water, it must receive nourishment from elsewhere. The cotyledon is the fatty portion of the seed that holds nutrients for the seed to survive on until it has germinated and has begun to sprout into the surrounding soil.
The radicle is the portion of the seed that emerges from the seed during germination. This is the first portion of the seed to emerge from the testa.
The plumule is a leaf-like growth that appears during the seed's development into the plant. The space between the radicle and the plumule is called the hypocotyl, which develops into the stem of the plant as it grows.