Tropism and nastia

It is possible that you have ever heard about in topics related to tropism and nastia plants . They are somewhat strange and purely scientific terms, but they are widely used in the field of biology and botany.

Surely if you learn these terms, you are closer to knowing the world of plants and understanding them better. Do you want to know what these two terms are about?


  • 1 Tropism
  • 2 the nastia



Tropism is the displacement carried out by plants (or sometimes only certain organs of it) to respond to a stimulus from the outside. Because there are different types of movements and displacements, there are several types of tropism, also depending on the nature of the stimulus to which it responds.

A first example is when the stimulus to which the plants respond comes from the force of the earth’s gravity and its acceleration. It is called gravitropism and it consists of the growth of the roots towards the ground while the stems develop upwards until they come to the surface.

Another example is phototropism by which plants react to light and allow the development of photosynthesis. The one that stands out the most is heliotropism, which is based on the movement of the plant according to the orientation of the sun. We find sunflowers that are able to move towards the sun to increase the rate of photosynthesis and be more efficient.

There are other different types of tropisms, such as chemotropism, which is capable of being able to link the responses of plants to chemical elements. For example, there are plants that are capable of moving to obtain certain chemical nutrients or, on the contrary, to “run away” from them. We also find stimuli such as air (aerotropism) in which plants orient themselves in the most aerated regions of the surface or water (hydrotropism).

the nasty


The nasty also corresponds to a movement of the plants responding to stimuli. So how are the two terms different? The basic difference between a tropism and a nastia is that in tropism, the response to stimuli is continuous, that is, they always do . For example, in aerotropism, plants will always grow and move to places with more air. However, in nastia, the response to external stimuli is carried out only for a few hours or a few minutes.

Also in nastia, the direction of the stimulus does not influence the movement of the plant . For example, we have carnivorous plants that are capable of responding to a stimulus such as the fact that the insect lands on the leaf, but it only does so for an instant. Once it responds to the stimulus, it returns to the starting position.

Among the examples of the nastias we have tigmonastia which is the movement of the plant in temporary response to contact with it. There are plants that by the simple fact of touching them move. This response indicates that the plant is more sensitive to changes in the environment.

We also have other plants that move due to excess humidity or, on the contrary, due to lack of humidity. It is called hydronasty and only occurs when changes in humidity occur. If there are no changes, there is no movement. However, in hydrotropism the plant did always grow in the direction where there is more water.

Another type of nastia is nictinastia, also better known since it is the opening and closing of plant leaves depending on the day and night. Or thermonasty, which is about movement depending on the temperature of the environment.

As you can see, plants also respond to external stimuli from the environment. There are plants that grow looking for the most optimal conditions of air, food, water, etc. And others that are capable of moving to be able to feed, protect themselves or act at a certain moment. With this you already know something more about the plants and you can be closer to them.

Tropism and nastia

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