How do climbing plants know where to climb? » ABC Science

How do climbing plants know where to climb?  » ABC Science

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The tendrils are sensitive to touch. More formally, tendrils show thymmotropism. They can change the direction of plant growth in response to the touch of a solid object.

In the world of botany, climbing plants quite literally “stand out.” They are tenacious acrobats who cling and turn around any form of physical support to survive and explore. I don’t want to be too philosophical, but the ability of vines to grow in unexpected places and stand up against all odds can be a lesson for all of us. Whether it’s your porch grill, the walls of an abandoned building, or a huge tree in the heart of the forest, they will cling to almost anything to grow.

Climbing plants can use almost anything as support for circulation and growth. (Image source: Sergey V. Kalyakin / Shutterstock)

Don’t worry, you’re not the first person to find climbing plants adorable. It turns out that human evolution wasn’t the only thing that intrigued Charles Darwin. He studied these amazing climbing plants and ended up writing an entire book about them.

Climbing plants have a unique organ that makes them superior to other plants in terms of “habitat selection.” Quite simply, they are in possession of tendrils. Tendrils are thin but strong filamentous threads that grow from the stem or leaves of a plant.

Hairy branch of a pumpkin plant climbing into a coconut
Hairy branch of pumpkin plant climbing on coconut rope with tendrils (Image Source: AjayTvm / Shutterstock)

Vines or climbing plants depend on external support structures to grow. Thanks to tendrils that extend outward to search and cling, climbing plants are able to find support that enables them to survive. Now, how do they know if there’s anything worth climbing on in the first place? It’s not like they have binoculars they can pull out to scan their surroundings for a pole or plant.


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How to find vines and creepers support?

The gentle winding threads on the plant play a crucial functional role. Tendrils are pretty much useless if they can’t find anything to cling to, but tendrils help them find support to cling to.

The tendrils are sensitive to touch. More formally, tendrils appear Thigmotropism. If you break up the word, thigmo It means “touch” and tropism It refers to “the act of growth or movement of a plant in response to external stimuli.” Essentially, tactile tropism is the change in the direction of plant growth in response to the touch of a solid object.

Thigmotropism comes in two types: positive and negative. The roots show negative thymmotropism. When the roots “feel” something in the soil, they move away from it. This allows the roots to spread toward empty pockets where there may be water.

Differential growth allows a plant to change its growth direction
Differential growth allows a plant to change its growth direction

Movement in tendrils does the opposite of what it does in roots. The tendrils of climbing plants show positive tropism for stress. When the tendril senses a solid object, it moves toward the tactile stimuli. It then wraps itself around said body and continues to grow on it. Through differential growth, the plant bends toward the body and wraps itself around a source of support. To learn more about psychotic tropism, click here.

Read also: What is psychotropism?

Do they know what they are climbing on?

Plants lack the sophisticated neural networks of the mammalian brain, but they are still able to perceive their surroundings. This awareness teaches them which plants can be climbed and which ones they should avoid.

It is very common for climbing plants to come across plants of their own kind. In the race for survival, rallying around a plant of the same species seems counterproductive. Plants of the same species pose a threat, because they will act as stronger competitors for space and resources, compared to plants of different species.

In addition, due to the fact that climbing plants themselves lack a strong stem to support their growth, clinging to a plant of the same species seems pointless. It’s like using a twig as a walking stick. Therefore, in light of natural selection, moving away from a plant of the same species seems like a smart choice.

Keratia japonica
Keratia japonica A plant containing high levels of oxalate (Image source: KENPEI/Wikimedia Commons)

According to a study conducted at the University of Tokyo, climbers can distinguish between plants of their own kind and other species. They found tendrils C. japonica Oxalate can be tasted. Oxalate is a chemical found in large quantities in the same plant. When oxalate is tasted on the supporting structure, the plant backs down and moves away from that plant. On the other hand, the plant did not avoid wrapping itself around sticks coated with chemicals such as agarose or citric acid.

Scientists believe that the ability to sense chemicals may be widespread among this group of plants.

Read also: Can plants hear, smell, see, touch or taste things?

Conclusion

As it turns out, climbing plants are more complex than we first thought. Not only can they change the direction of their growth based on tactile stimuli, but they can also determine whether the support they plan to climb on belongs to the same type or not. Some plants choose a plant to support based on the diameter of the stem. For example, a plant like Wisteria sinensis It will not climb on another plant wider than 15cm!

References (click to expand)
  1. Thigmotropism in tendrils – Biology – Kenyon College.
  2. Giannulli, E. (2015, January 1). Behavioral ecology of climbing plants. Ob plants. Oxford University Press (OUP).
  3. Fukano, Y. (2017, March). Vine tendrils use contact chemoreception to avoid leaf-marking. Proceedings of the Royal Society B: Biological Sciences. Royal Society.

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