All plants have life cycles, but there is considerable variation in the details across the plant kingdom. Some, like ferns that are non-flowering plants, have life cycles that are dramatically different from that of the pea plant. Among flowering plants, though, the pea plant is fairly representative of many other kinds of plants, especially relatives, like the bean plant.
The pea plant's flower is a so-called perfect flower. Botanists use that term to refer to flowers that have both male and female components within one flower. Not all plants have perfect flowers; some even have the male and female flowers on separate individual plants.
Unlike some plants that are wind-pollinated, the pea plant's flowers are insect pollinated. The insect visits the flower, attracted probably by the colour, the shape and the nectar the flower produces. Upon visiting, the insect transfers pollen produced by the flower's male parts, called the anthers, to the female part. The pollen then fertilises the egg within the female part of the flower.
Once fertilisation has occurred, the fruit begins to develop. In the case of the pea plant, the fruit is the familiar pea pod. Contained within the pod are the individual peas, which are the plant's seeds. If the pea seeds survive to maturity without being eaten, being attacked by a disease organism, or succumbing to a drought or other calamity, the seeds will mature and be ready for germination.
Under favourable conditions, the pea seed will germinate. Perhaps the most important factor in seed germination is the presence of moisture. Moisture is what stimulates the seed coat to split open. Soon after germination, the young pea plant develops a root and a shoot. The root anchors the plant and supplies nutrients and water to the above-ground parts of the pea plant. The shoot initially has two so-called cotyledons, or seed leaves. These soon wither, and true leaves begin to develop.
The young pea plant continues to grow and eventually becomes mature enough to flower. Once flowering has taken place and the flowers are pollinated, new pea pods develop and mature, complete with peas (seeds) inside. Again, if these this new generation of pea seeds makes it unscathed to maturity and germination, the pea's life cycle is complete.