Plants are vital for human survival, producing oxygen, taking in carbon dioxide and making the world a better place to live. A tiny seed with some water, sunlight and nutrient grow into a full-fledged plant, but there is one peculiar thing you must have noticed that a plant always grows in upward direction. Have you wondered why only upward? Read on to understand this nature’s phenomenon.
When a plant germinates from a small seed it emerges from deep under the soil as a shoot, but how come it grows only in upward direction and not in the left or right direction?
A plant contains certain stimulus that plays a crucial role in the process and one such stimulus is tropism. Tropism is how a plant responds to certain stimuli like light, touch and gravity. Plant parts are very much sensitive to geotropism, a phenomenon which is not yet fully understood by researchers. Tropism acts on different internal and external parts of plants to grow them in different directions at the same time. This particular phenomenon is responsible why roots grow in downward direction and shoot in upward direction.
There are two types of geotropism that act on plant growth, one is positive geotropism which act on roots causing downward growth and the other is negative geotropism responsible for shoot development. The shoot experience negative geotropism and resist the gravitational pull. The shoot grows longer with the help of hormone called auxin which is present in many parts of the plant in larger concentration. Auxin stimulates the cells in such a way that it grow towards the light.
One other interesting fact that too make the plant to grow upward is phototropism, where the plant grow towards the sun and sun’s energy become the most important part for growth and development.
