If you have any plants indoors, you may notice that their stalks bend and turn towards the light. To keep the plant’s shape, you may have to turn it around until it once again bends towards the light. Plants turn towards the light automatically, growing in that direction.
These movements allow the plants to get their energy from the light. When a plant bends toward the light, this is because the plants are growing. When they are growing, they release internal chemical substances. This growth hormone is called an auxin. Auxin comes from Greek and means ‘to grow.’ When a plant bends towards the light, this is called phototropism.
If one side of a plant is in the shade, the plant produces a growth hormone. The growth hormone is passed to the darker side of the plant, causing it to grow quicker than the side in the light. This growth causes the stem to bend towards the light.
As plants mature, their reaction to light also can change. Some plants will continue to bend towards the light as they mature. However, once fertilized, others will not grow towards the sunlight but will use the energy from the light to grow into the soil. Many plants that produce fruit or vegetables under the earth will put their energy into the stalk in the soil to grow their fruit.