Thigmotropism: Definition, Types, and Example

Thigmotropism Definition

Thigmotropism is a directional growth movement that occurs as a mechanosensory response to a touch stimulus. Thigmotropism is typically found in twining plants and tendrils, however, plant biologists have also found thigmotropic responses in flowering plants and fungi.

What is Thigmotropism?

It is also known as haptotropism, thigmotropism is the directed growth movement or change in the orientation of plant growth in response to touch. The orientation factor is generally a hard surface that can change the direction of plant growth or the growth of any of its organs.

Thigmotropism can take the form of opening or closing parts of plants such as petals or leaves, wrapping the plant around the surface, or in some other way. Thigmotropism can be used in a way that increases the likelihood that a plant will capture the light for photosynthesis.

Thigmotropism is an example of tropism, where a plant responds to environmental stimuli by growing towards or away from them. In other words, the reaction can be positive or negative. For example, a stem can grow up towards the sun and roots can grow away from an object in the ground.

Other forms of tropism are phototropism, a reaction of the plant in response to light. Thigmotropism typically occurs in twin plants and tendrils. However, plant biologists have also found thigmotropic reactions in flowering plants and fungi.

thigmotropism

Types of Thigmotropism

Differential Growth

Differential growth signals that one side of the plant is growing faster than the rest of the plant when stimulated. Specialized epidermal cells cause these different growth rates, and this is reflected in the growth pattern of the tendrils. Differential growth can occur within minutes and is usually long-lasting.

Rapid Contact Coiling

Rapid contact coiling, on the other hand, is an instant response. It happens quickly and doesn’t last long. An example of this is the folding of the leaves of some plant species upon being touched. In some cases, rapid contact coiling occurs first and is then followed by the slower and more permanent differential growth.

Examples of Thigmotropism

An example of thigmotropism is the coiling movement of tendrils in the direction of an object that it touches. On the other hand, the folding movement of the Mimosa pudica leaflets can be considered as an example of thigmonastism.

Thigmotropism is an example of tropism and can be positive or negative. Positive thigmotropism is a response to the touch stimulus, while negative thigmotropism is a response away from the touch stimulus.

The drooping of Mimosa pudica leaflets when touched is not considered a thigmotropism but rather an evil movement. This is because the response of this plant is not affected by the direction of the stimulus, which is characteristic of thigmotrophic movements.

There are a few different ways that different climbing plants use to cling to surfaces and to change their own shape. The two examples of thigmotropism that will look at are the presence of tendrils, and the clinging of plants to surfaces using their roots.

Tendrils

A tendril is a thread-like structure that occurs in climbing plants and serves as a support. It is a modified leaf, stem, or petiole that has a winding as a form of thigmotropism. An example of a plant with tendrils is the Humulus Lupulus or common hop shown below. It is an herbaceous climber that can grow very quickly and its tendrils wrap around the carrier in a clockwise direction.

Tendrils begin to flex in search of a surface to grow over. Once they find it, the part of the tendril that is in contact with the surface produces a hormone called auxin, which stimulates a large area on the tendril that is not in contact with the surface to grow. In addition to auxin, the hormone ethylene supports growth and controls the shape of the cells.

The overall process causes the cells that touch the support surface to contract or grow more slowly, while those that don’t touch them to expand or grow faster. The different growth rates on different sides of the plant result in the curling that occurs around the supporting object.

In order for a plant or a plant organ to experience constant growth, continuous contact with the surface is necessary. Finally, note that tendrils need light to respond to touch, so they receive a stimulus in the dark and cannot react until the light is available.

Thigmotropism in Humulus Lupulus
Thigmotropism in Humulus Lupulus

Clinging Roots

Some plants climb trees with their roots. The hedera genus of woody plants, or what we call ivy, is an example of this. It includes a number of species that will crawl or climb the ground when a suitable surface is found. Ivy often use trees as a climbing surface, as shown in the picture below, and can be overwhelming and harmful if grown excessively over them.

In some regions, they can also be considered an invasive species. They have stem roots that change their arrangement and produce tiny root hairs to hold them in place, and ivy is believed to have additional means to adhere strongly to surfaces.

The hedera genus of woody plants, or what we call ivy, is an example of thigmotropism. It includes a number of species that will crawl or climb the ground when a suitable surface is found.
Thigmotropism in Hedera Genus
What is Thigmotropism?


Thigmotropism is a directional growth movement which occurs as a mechanosensory response to a touch stimulus. Thigmotropism is typically found in twining plants and tendrils, however plant biologists have also found thigmotropic responses in flowering plants and fungi.

What are the Types of Thigmotropism?


A positive thigmotropism is a response towards the touch stimulus whereas a negative thigmotropism is a response away from the touch stimulus. Examples of positive thigmotropism are the growth of ivy on walls upon contact to walls and the coiling of tendrils or twiners upon contact to objects for support.

Examples of positive thigmotropism include the growth of ivy on walls when in contact with walls and the curling of vines or twins when in contact with objects for support. An example of negative thigmotropism is the growth of roots underground. When an elongated root comes into contact with an object, e.g. Stone, it grows away from the object.

What is the example of Thigmotropism?


An example of thigmotropism is the coiling movement of tendrils in the direction of an object that it touches. On the other hand, the folding movement of the Mimosa pudica leaflets can be considered as an example of thigmonastism.

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