Pea plants (Pisum sativum) are part of the Leguminosae family. Peas are an easy to grow vegetable which are planted commercially and in home gardens all over the world. Peas have adapted over time to ensure the continuation of every species, and a part of this edition is the ability to reproduce in two ways: self-pollination or cross-pollination.
Peas are cool season plants hardy in U.S. Department of Agriculture hardiness zones 3 through 11. They reproduce in a life cycle known as an alternation of generations, which means that they have haploid and diploid phases at different times in their life cycle. Haploid describes when plant tissues have one set of chromosomes, and diploid describes when plant cells possess two sets of chromosomes. Peas are angiosperms, or flowering plants, and have separate male and female pieces. The male portion of the pea plant is called the stamen, which is made up of the filament and the anthers. The feces which fertilize the female parts are in the anthers. The feminine portion of the pea plant is called the pistil, which contains the style, the stigma and the ovary. In order for the pea plant to reproduce, the pistil has to be fertilized by the pollen grains.
Self-pollination takes place when the flowers are shut and pollen from the plant falls on the female ovary of the same plant, and this occurs before the flowers open. This adaptation also reduces the chance of genetic variability. Peas, in addition to beans, peanuts, tomatoes, eggplant, peppers and lettuce are mainly self-pollinating.
Cross-pollination takes place when a pollinator, including a bee, enters the plant to drink nectar and picks up pollen grains while it’s there. When the pollinator goes into the next blossom, these grains are transferred to the pistil and the flower is fertilized. Some plants are also cross-pollinated by end, which picks up the grains and disperses them in the open flowers. While pea plants might be pollinated in this manner, it is rare because self-pollination often occurs before the blooms open. However, North Carolina State University recommends putting peas 10 or more feet apart to stop cross-pollination between different varieties.
Along with self-pollination, pea plants have created other adaptations to ensure their success. Pea plants have formed beneficial relationships with fungus and bacteria as well, providing sugars made inside the plant to the following soil organisms. In return, pea plants receive hydrogen in a readily accessible form in the bacteria and an increase in the uptake of nutrients in the soil in the fungus.