Pea plants are annuals, meaning that they complete their life cycle, from germination to the formation of new seeds, within one year. They are part of the legume family, or scientifically speaking, the Leguminosae. Peas are easy to grow and are commonly used in classrooms to teach children about plant biology.
A pea plant starts out as a seed. Seeds need water, warmth and to be planted in a good location in order to germinate. Once those needs are met, the outer shell of the seed softens, and a tiny root begins to grow downward. This root will start to take nutrients from the soil to help the seedling grow.
At the same time a small shoot starts growing upward. One the seedling breaches the surface of the soil, its tiny leaves unfold and begin the process of photosynthesis. The leaves and stems contain chlorophyll, which converts the sun's light and carbon dioxide into sugar which the pea plant will either store or use for food.
The pea plant continues to grow, and since it is a climbing plant, it sends out long tendrils that reach out and cling to fences, poles or even taller plants. Meanwhile, the root is getting just as big underground, drawing in nitrogen from the soil through bumpy nodules along the root's surface.
Flowers develop that contain both male and female reproductive organs. The male organs, called the stamens, holds pollen on the sticky ends, called anthers. The female organs, called styles, contain the ovaries, where the future seeds will grow, and the stigma, the sticky end where the pollen is deposited.
Though pea plants are self pollinating, they do produce scented white and purple flowers to attract bees and other insects.
Once the pea plant has been pollinated, the process of fertilization begins. The pollen grains travel down the inner tube of the style to the ovary. These grains then fertilize the ovules, which will become the seeds.
The flowers wilt and fall away, and the ovary swells, providing a protective covering for the future seeds. In peas, this covering elongates, resembling a long, almost circular tube. When the seeds are mature, they can be felt, and seen, through the outside walls.
Peas grown for agricultural production are usually harvested before the seed pods dry out. The peas we eat are immature seeds. Those pods left on the vine will eventually dry out and split, dropping the similarly dried seeds on the ground. The original plant withers and dies. The new seeds are usually thrown far enough away from the parent plant to ensure good seed dispersal. Once conditions are right, the new seeds will germinate, and the cycle begins again.