OxScience

Nastia

It is a temporary movement of certain organs of a plant before an external and diffuse stimulus. It is based on the growth processes or turgor changes of various cell thicknesses that vary their volume through the control of the entry and exit of water.

They are active and reversible movements, they are not oriented towards the stimulus so they do not act in the direction in which the plant should react.

It mostly affects flat organs such as petals, tender leaves, and longitudinal growth organs such as branches, tendrils, among others. They are classified into:

Photonastia: In response to light, flowers open or close their petals at dawn or dusk.

Geonastia: It is produced by gravity and the physiological dorsiventrality of the plant organ.

Haptonastia or tigmonastia: It is the response to contact, it occurs in the tendrils of many plants. There is a growth of the flank opposite the contact.

Hydronastia: It is the response to humidity in the environment.

Chemionastia: It is the response to chemical agents.

Nictinastia: The position of the leaves varies with day and night.

Sismonastia: It is the response produced by a blow or shake on the vegetable. An example is the movement of carnivorous plants or certain mimosa.

Thermonastia: It is the response to variations in temperature.

Traumatonastia: It is produced by an injury or as a consequence of it.

Tropisms

It is the movement made by plants or their organs to respond to an external stimulus. The tropism can be positive when it accompanies the stimulus and negative when the reaction is opposite to the stimulus. There are several types of tropisms depending on the nature of the stimulus:

Gravitropism: It is responsible for bringing the roots to the ground and that the stems develop upwards until they come to the surface.

Phototropism: Plants react to light, going to the area with the best lighting.

Heliotropism: It implies the movement of the plant according to the orientation of the sun.

Chemotropism: It is the response to the chemical elements that a plant needs or that harm it.

Thermotropism: They lead plants to move at a specific temperature.

suggested video: Nastia vs tropism 

Difference between Nastia and tropism

• A tropism is the response of a plant or animal to a stimulus that makes them orient themselves with greater intensity towards the stimulus or to flee from it.
• Nasties are rapid and reversible movements of a plant when faced with an external stimulus. However, the direction of the stimulus does not influence them.