Life is a balance between various activities. These activities include growth, nutrition, reproduction etc. Animals and plants are two entirely different forms of living organisms. Hence the pathway they follow for various life processes are also different even though there are some similarities. For example, animals can run away from its predators but plants can’t. Plants have their own mechanism to counteract the danger they face.
Let us see Tropic movements in plants and how plants control and coordinate in brief.
Nervous system and endocrine system are the two systems in animals to balance and control all the activities but plants are devoid of the nervous system and other organs. However, plants learn to respond to different stimuli by certain movements. This response may be rapid movements like seismonastic movement or slow process like tropism. Sensitive plants show seismonastic movement in response to touch. Thus we can classify plant movements into two: tropic and nastic.
When a plant shows some growth movement in response to a stimulus, it is known as tropism. Tropism is direction specific and depends on the direction of stimulus. Plants may either show positive or negative movement as a response to a stimulus. If the movement is towards the direction of stimuli, it is known as positive tropism while movement away from stimuli is known as negative tropism. Certain types of tropism are as follows:
Phototropism: Plants grow towards or away from the light, this type of tropism in the response to light is called phototropism. Stems show positive phototropism while roots show negative phototropism.
Gravitropism: It is a type of tropism where plants show some growth in response to gravity. Stems are negative to gravitropism while roots are positively gravitropic. This is also known as geotropism.
Chemotropism: When plants grow in response to certain chemicals, the type of response is known as chemotropism.
Thigmotropism: A type of tropism in response to touch is called Thigmotropism.
These types of tropism help plants to be more adaptive and help in survival. The positive response of stems towards light helps plants in photosynthesis and positive gravitropism of roots helps in the absorption of minerals and water from the soil.
Nastism: Growth Independent Movements
In some situation, plants have to respond spontaneously without any growth. Such growth independent movements are commonly termed as a nastic movement. Certain plant hormones or electrical impulses are responsible for this movement.
For example, rapid folding of touch-me-not leaves. Plant cells transfer electrical impulses and there will be a change in water concentration in leaves. In response to this, cells adjust their shapes. Other examples include lotus plants, Venus flytrap etc..
Plants are a most adaptive form of life. They have developed their own way of survival. Tropism is one among them.
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