How a Bean Plant Grows

Germination

• To germinate, bean seeds need to be planted in warm soil and kept moist. The seed pulls in this moisture, signaling several reactions. First, the seed's covering ruptures, then the embryo releases hormones that trigger enzymes to begin metabolizing the seed's energy stores. The seed uses the energy to become a seedling.

Becoming a Seedling

• The seed first develops a primary root called the radicle. This extends into the soil to form true roots as a shoot pushes up through the soil. The end of this shoot holds the remaining pieces of the seed, which will soon sprout the seed leaves. These seed leaves photosynthesize to provide energy for the seedling to produce its first true leaves.

Growing

• Provided regular water and plenty of sun, the seedling continues to add leaves and height. Growth occurs through cell enlargement and division. Signals within each cell tell it to become a root cell, leaf cell, flower cell and so on. When the plant is mature and conditions are right, the bean plant flowers. In some varieties of bean, all the flowers appear at roughly the same time. In others, the flowers bloom over several weeks. This timing is determined by the plant's genetics.

Flower to Fruit

• Once the bean blooms, the flowers are pollinated by insects, birds and sometimes the wind. Pollen travels into the female parts of the flower to fertilize the eggs in the flower's ovary. After fertilization, hormones and enzymes signal the flower to fade and for the ovary to develop into a pod. When you eat green beans, you are eating the ovary before seeds can develop. Left on the plant, further changes signal the growth of seeds (beans) within the pod.