Life Mechanisms of Plants

Nature around us is amazing. Nature is beautiful because it has wide variety of flora and fauna. When we look and observe the beautiful Nature around us we see several types of plants, flowers. These plants are a gift of Nature to mankind because:

Earth is called a green planet due to presence of plants on it. Without plants, there can be no environment and human life on this earth. Their presence is inevitable for clean air, food and water. They minimize gaseous pollution. Rainfall, humidity and temperature are influenced by plant life. They balance the proportion of oxygen in the air.

Plants are useful as food, medicines, clothes, shelter, medicines, spices, beverages forest products, insecticides and pesticides.

They provide shelter for animals and birds. Plants are the source of essential oils which are used in perfumes.

Plants prevent soil erosion, increases fertility of soil, bring in rainfall, cools hot climate.  Thus, plants have such abundance of goodness in them.

Plants are living things. They have seven life processes. They are nutrition, respi­ration, excretion, sensitivity, move­ment, reproduction and growth. A few other characteristics of the plants are life cycle, death, adaptations evolution and homeostasis.

All plants grow towards sunlight is a sensory activity of the plants. They move towards sun light because they require sunlight for photosynthesis. This can be seen when a plant is kept inside a room, it grows towards the window in search of sunlight. Often, we have seen trees are grown bending towards sunlight. Plants do not grow under the thick canopy of trees for the want of sunlight. Even if some plants are growing, they do not depend on sunlight for photosynthesis. The growth of a plant towards any stimulus is called tropism, and the growth of a plant toward a light stimulus is called phototropism - photo means light.

Auxins are produced in the meristems of plants. They are responsible for promoting cell elongation, a process that is required before differentiation of a cell. It increases the elasticity of the cell to cope with the increase of water taken in by the cell.

One of the most common Auxins is Indoleacetic Acid.

Auxin increases the flexibility of plant cell walls that limits the plant cell growth. As a consequence, plant cells tend to grow faster in the presence of Auxin. When a plant senses a directional light stimulus it redistributes its auxin molecules to the side that is further away from the light. So, the plant cells that are further away from the light experience a greater auxin concentration and grow faster, causing the shoot to bend towards the light. This mechanism allows plants to optimize the amount of light they receive in order to increase rate of photosynthesis.

Roots of the plants moving towards gravity are another sensory activity. This 

is called Geotropism or Gravitropism.  Geotropism or Gravitropism  is the  

growth of the plants towards gravity. Roots bend in response to gravity due to 

a regulated movement of the plant hormone Auxin.

In the root cap there are special cells, called statocytes. Inside the statocytes, there are some specialized amyloplasts to percept gravity. These specialized amyloplasts are called statoliths. They are denser than the cytoplasm and can deposit themselves according to the gravity. The signal of earth gravity leads to the reorientation of auxin carriers and subsequent redistribution of auxin streams in the root cap and root as a whole. The changed orientation in concentration of auxin leads to differential growth of the root tissues. That means that the root is then turning to follow the gravity stimuli.

Statoliths are also found in the endo-dermic layer of the inflorescence stem. The redistribution of auxin causes the shoot to turn in a direction opposite that of the gravity stimuli.

Mimosa Pudica or Touch- Me- Not plant is sensitive to touching or shaking the plant. The leaves of the plant shrink and close its leaves upon touching.  The opening and closing of the plants' leaflets and the entire leaf are controlled by a fluid filled sac-like structures found at the base of the compound leaf of each leaflet.

The swollen base of the leaf stalk is called `pulvinus'. When the plant is touched, electrical signals are flashed by the cells. The cells in the `pulvinus' respond to this signal by flushing out potassium and water. With the massive loss of water, the pulvinus bends over and the leaflets fold. The responses of this plant were first observed by Indian scientist Jagdish Chandra Bose to prove that plants also feel pain.

The pitcher plant grows in locations where the soil is too poor in minerals or too acidic for them to survive. The Pitcher Plant doesn't rely on just glucose to survive, They also need other micronutrients and minerals, and things which they normally obtain through their roots, which they are getting from the nutrients of the insects they are eating.

The Pitcher plant closes its colourful lid and engulfs the fly when a fly just sit on the lid.  The rim of the pitcher is slippery. It is moistened by nectar, causing insects to fall into the trap. Pitcher plants may also contain waxy scales, protruding  aldehyde crystals, cuticular folds, inward and downward pointing hairs, or guard cells. There are certain cells on the inside of the pitcher which ensure that insects cannot climb out. There are small bodies of liquid called phytotelmata inside the pitcher to trap the insects. Phytotelmata drown the insects and dissolve them.

Plants do not have specialized structures to perceive sound or any other sensory activities. According to the new study, they can understand the humming sound of bees and moths by the vibrations caused by their leaves. They also can understand attacks by their predators.

Plants are very close to the environment where they are living. Their constant exposure helps them to understand the changes happening in the environment. Though they do not have brain and a well-developed nervous system they can communicate with each other by releasing chemicals in the air about some impending danger to their community.

Sir Jagdish Chandra Bose proved that plants have feelings. They respond to various stimuli like pain, pleasure, hug, affection etc. Likewise when melodious music is played continuously for a few days to the growing plants their growth becomes obvious in few days.

When plants and trees are hugged and their leaves are touched with love and affection they grow very well. On the contrary, if we use harsh words against them then there will be stunted growth and they may even die one day.

Plants interact with their environment and their group members. If we observe plants very closely they respond very well with our emotions, likes and dislikes. They understand rains, storms, flood and wind. We have to make an effort to understand them and their behaviour towards Nature.

From all the above examples cited we can understand that plants have feelings, they understand music, happiness, anger, etc. They can identify predators, enemies and any foreign element in their environment. They also understand weather change and they cannot resist climate change. That is why they become endangered.

All these facts prove that plants sensory organs are very minute and very delicate. They may not have well-defined sensory organs to hear or to see. But they can feel and understand. Research is required to establish how and why of their sensory activities. By careful observation and research we have to understand the life style of the plants. We have to learn to co- exist with the plants to make this Earth pleasant and beautiful place to live.