Can Plants Move? - Tropic and Nastic Movements

Yes, plants can move, but their movements are different from those of animals. Plants cannot move from one place to another, but they are capable of a variety of movements, classified into two main groups: nastic and tropic movements.

Nastic movements are undirected plant movements that are triggered by changes in environmental factors such as temperature, humidity, light, and touch. These movements involve changes in the size, shape, or orientation of plant organs in response to the environmental stimulus. Examples of nastic movements include the closing of the leaves of a Venus flytrap (Dionaea muscipula) in response to prey and the opening and closing of flowers in response to changes in temperature and light.

In contrast, tropic movements (also known as tropism) are directional movements that are triggered by the direction of a stimulus, such as the direction of light or gravity. Tropical movements can be either toward or away from the stimulus and are typically growth movements that involve changes in growth rate or direction of plant organs. Examples of tropical movements include the growth of plant roots toward water sources and the bending of a plant stem toward light sources.

There are several types of nastic movements observed in plants, each with its own unique mechanism and function. The suffix "-nasty" is commonly used to name nastic movements, with prefixes that vary depending on the type of stimulus that triggers the movement.

Let us take a closer look at some of the most common nastic movements observed in plants:

• Photonasty: this movement is triggered by changes in light intensity. An example is the opening and closing of flowers in response to light.
  
  
• Thermonasticity: this movement is triggered by changes in temperature. An example is the opening and closing of some flowers and leaves in response to temperature changes.
  
  
• Seismonasticity: this movement is triggered by mechanical stimuli such as touch or vibration. An example is the sudden movement of leaves in response to touch.
  
  
• Nyctinasty: This movement is triggered by changes in the light-dark cycle. An example is the opening and closing of some flowers or leaves in response to the daily cycle of light and dark.
  
  
• Thigmonastia: This movement is triggered by sustained mechanical stimulation, such as contact with an object. An example is the movement of tendrils in response to contact with a support structure.
  
  
• Hydronasty: this movement is triggered by changes in water availability or humidity. An example is the opening and closing of some flowers in response to changes in humidity or water availability.
  
  
• Chemonasty: This movement is triggered by chemical stimuli, such as the presence of certain gasses. An example is the movement of some plants in response to ethylene gas.
  
  
• Thermanasty: This movement is triggered by temperature changes, similar to thermonasty. However, the reaction is slower and occurs over a longer period of time.
  
  
• Chrononastia: This movement is triggered by temporal changes in environmental factors, such as changes in the diurnal cycle of light and dark. An example is the opening and closing of some flowers at certain times of the day.

You may also be interested in this other article, where we discuss what annual flowering plants are.

Tropic movements can be classified based on their orientation relative to the direction of the stimulus. The two most common types are positive tropisms, which involve growth towards the stimulus, and negative tropisms, which involve growth away from it. Both of these types are considered orthotropic. In contrast, tropisms that grow perpendicular to the stimulus are called diatropic, while those growing at an oblique angle are called plagiotropic.

Let us take a closer look at some of the most common tropic movements in plants:

• Phototropism: this is the growth response of plants towards a light source. The shoot tip of the plant bends towards the light, while the roots grow away from it.
  
  
• Geotropism: this is the growth response of plants to gravity. The shoots grow upwards, against gravity, while the roots grow downwards, towards gravity.
  
  
• Thigmotropism: this is the growth response of plants to touch. The plant's stem or tendrils grow around an object they come in contact with, providing support for the plant.
  
  
• Hydrotropism: this is the growth response of plants towards water. The roots grow towards a source of water, even if it means growing horizontally or upwards.
  
  
• Chemotropism: This is the growth response of plants towards chemicals. The roots grow towards nutrients in the soil, and pollen tubes grow towards the ovule in the flower.
  
  
• Thermotropism: This is the growth response of plants to temperature. For example, some plants, such as the skunk cabbage, generate heat to melt snow and attract pollinators.
  
  
• Aerotropism: this is the growth response of plants to air. For example, some plants such as the Venus Flytrap close their leaves to trap insects that they use as a source of nutrients.
  
  
• Galvanotropism: this is the growth response of plants to electric fields. Plants can sense and respond to electric fields in their environment, such as those generated by lightning.

Do not miss this other article about what gymnosperms plants are.

Nastic movements are undirected movements that occur in response to environmental factors such as temperature, humidity, light, and touch.

In contrast, tropical movements are directed movements that occur in response to the direction of a stimulus, such as the direction of light or gravity.

Nastic movements are changes in the size, shape, or orientation of plant organs in response to an environmental stimulus, which may be due to changes in turgor pressure in plant cells. These movements play a critical role in plant survival.

Tropical movements, on the other hand, typically involve changes in the growth rate or direction of plant organs and are growth movements.

Similarities between tropic and nastic movements

Although nastic and tropical movements are different types of plant movements, they have some similarities.

• Both nastic and tropical movements are adaptive responses that allow plants to respond to changes in their environment.
  
  
• Both nastic and tropical movements can be influenced by a variety of environmental stimuli, including light, gravity, touch, and moisture.

While there are clear differences between nastic and tropic movements, they share some commonalities that highlight the remarkable capacity of plants to respond and adapt to their surroundings.

Do not miss this other article about what are compound leaf in plants.

If you want to read similar articles to Can Plants Move? - Tropic and Nastic Movements, we recommend you visit our Biology category.