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(pictures from the Internet) in our third-grade Chinese textbooks, there is an article called "the feet of Parthenocissus" by Grandpa Ye Shengtao. A paragraph in the article reads: "it turns out that Parthenocissus has feet." Parthenocissus' feet grow on the stem, where the petiole grows on the stem, and six or seven filaments protrude on the opposite side, each of which looks like a snail's antennae. The filament is as red as the new leaves. These are the feet of Parthenocissus. "

The author tells us about the climbing process of Parthenocissus with literary strokes, so let's explore the mystery from a scientific point of view.

How does Parthenocissus climb? On the stem of Parthenocissus, several small "thin lines" grow intermittently at the nodes of the stem, opposite to the leaves of Parthenocissus, just like the "legs" of Parthenocissus. The "foot" of Parthenocissus is actually something similar to a sucker, each of which is connected by a "thin thread", forming its complete action force. These "thin lines" stretch straight at first, and when Parthenocissus needs to cling to and climbing, its "feet" stick firmly to the surface of the wall, and the "thin lines" bend into tendrils.

"legs" and "feet" of Parthenocissus wikipedia because Parthenocissus has many tendrils and can climb upward with more "feet", it grows very fast and covers a wide area. Every time a tendrils grow, the ivy will climb up a little bit, clinging to the wall, waiting for the elongation of the stem and the new tendrils to grow again.

Wild growth of Parthenocissus | YouTube why can the creeper "climb"? Don't underestimate the delicate, slender tendrils and suckers. If you don't use your fingers, it's hard to pull them off the wall.

Photo Source: flickr. He Tianxian of South China University of Technology agrees with this. The team found in 2012 that the average mass of a single sucker of a mature and withered Parthenocissus is about 0.0005 grams, and the average adhesive contact area with the substrate is only 1.22mm, but its adhesive force is 13.7newtons. The weight of a single sucker during its growth and development is 260 times that of the sucker itself, and the maximum pulling force it can bear is 2.8 million times its own weight. In other words, Parthenocissus' foot can hold up a bottle containing 1.4 liters of water.

Sucker: I want to hold on to you! | the reason why YouTube Parthenocissus can be firmly attached to various surfaces needs to be explained in detail from two aspects. The first is the unique structural characteristics of the sucker.

After scanning the sucker of Parthenocissus with an electron microscope, the scientists found that before touching the object, the tip of the tendrils of Parthenocissus is bulbous, and a central area composed of a large number of parenchyma cells is the sucker. The surface is relatively smooth (Fig. A, b).

Scanning electron microscope images of tendrils and immature suckers | reference [4] the micropores inside the sucker secrete a large amount of viscous liquid when they first come into contact with the object, and the mucus gradually hardens over time (figure e).

Scanning electron microscope picture of immature sucker | reference [4] at the same time, the epidermal cells of the sucker near the contact point will stretch crazily, while other epidermal cells will remain oblique separate. so that the surface of the sucker will show a brush shape made up of a large number of "balloon clusters" (figure d, e, f).

These "balloon clusters" can be imitated according to the uneven surface of the object, thus further forming a "bite".

Scanning electron microscope pictures of immature suckers | references [4] secondly, a sticky substance is secreted from microtubules with an average diameter of 5 μ m and micropores of cavernous bodies with an average diameter of 5 μ m in the process of sucker adhesion.

Scanning electron microscope pictures of mature suckers [4] early studies have shown that Parthenocissus tendrils contain large amounts of polyphenols, while the sticky substance secreted by fully developed suckers is likely to be an acidic mucopolysaccharide. Later, with the development of compound analysis technology, scientists found that the mucus secreted by the sucker of Parthenocissus is mainly a kind of debranched rhamnus galacturonic acid polysaccharide and some new compounds synthesized in trace amounts.

A small plant is of great use.

Stretch your lazy legs secretly! | flickr "Parthenocissus is involved in chemical, biological, mechanical and other fields in the process of growth and development. The study of the microstructure and function of Parthenocissus sucker will promote the development of biomimetic materials and bionic devices, which is of great scientific significance." Professor Deng Wenli from the School of Materials at South China University of Technology said.

In 2015, according to the meaning of Parthenocissus climbing wall, a bionic dynamic exterior wall with heat insulation function was designed, which not only effectively blocks the heat of sunlight outside the wall, but also has the effect of dynamic decoration and beautification.

Bionic dynamic exterior wall structure with heat insulation function: 1-wall, 2-support bar, 3-blade | reference [7] in 2019, according to the characteristics of Parthenocissus adhesion, a bionic micron column array adhesion pad was designed, which can achieve strong adhesion and controllable reversible detachment on different rough surfaces.

SMP Biomimetic Micron column Array before and after Adhesion [2] in the same year, researchers from the Italian Institute of Technology (IIT) published a paper entitled "A tendril-shaped software robot driven by dynamic infiltration", showing us the world's first soft robot that mimics plant tendrils (not entirely similar to Parthenocissus). It brings a new idea for the driver research and development of software robot.

I roll, I roll, I crazy roll | reference [3] in 2021, according to the polysaccharide mucus secreted in the micropores of Parthenocissus mandshurica, a new "crystalline fiber reinforced polymer gel" was developed by Professor Wang Qigang of the School of Chemical Science and Engineering of Tongji University. This kind of gel breaks through the limitation of different interfaces when objects are bonded, so that more materials can be bonded through a general interface.

The figure of the crawling sucker shows that the mucus released from its microchannel can improve the adhesion strength. [1] in the same year, according to the structure of Parthenocissus sucker, a Parthenocissus bionic scaffold was invented for periodontal tissue regeneration. the bionic scaffold can effectively promote the formation of cementum-dentin interface.

The bionic research on Parthenocissus is still going on.

Photo Source: the unnoticed creeper in flickr's life has occupied the high walls of the city with its own unremitting climbing, and has gradually occupied a place in the field of scientific research. Is there any reason why we should not work hard?

The heart of Parthenocissus os: I also want to lie flat, but the minister "tiger" can not do it!

Reference:

[1] https://doi.org/10.1002/adma.202103174

[2] https://doi.org/10.1002/smll.201904248

[3] Must, I., Sinibaldi, E. & Mazzolai, B. A variable-stiffness tendril-like soft robot based on reversible osmotic actuation. Nat Commun 10344 (2019).

[4] he Tianxian. Study on the adhesion of Parthenocissus mandshurica [D]. South China University of Technology, 2012.

[5] Deng Wenli's team of South China University of Technology solved the mystery of Parthenocissus's super adsorptive power-- Science Times (2008-11-10)

[6] Zhang Li. isolation, purification, structural characterization and adhesion properties of Parthenocissus sucker polysaccharides. South China University of Technology. 2014. Doctoral thesis

[7] Shaanxi Institute of Technology. A bionic dynamic exterior wall with thermal insulation [P]. China: CN204753853U,20151111

[8] Shanghai Oral Disease Prevention and treatment Hospital. a Parthenocissus bionic scaffold for periodontal tissue regeneration [P]. China: CN214129678U,20210907

This article comes from the official Wechat account: take Science Home (ID:steamforkids), written by A Xian, revision: Shen Mengxi

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