Collenchyma Cells Provide Strength, Flexibility

Biological Strategy

Plants

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Manage Compression

When a living system is under compression, there is a force pushing on it, like a chair with a person sitting on it. When evenly applied to all sides of a living system, compression results in decreased volume. When applied on two sides, it results in deformation, such as when pushing on two sides of a balloon. This deformation can be temporary or permanent. Because living systems must retain their most efficient form, they must ensure that any deformation is temporary. Managing compression also provides an opportunity to lessen the effects of other forces. Living systems have strategies to help prevent compression or recover from it, while maintaining function. For example, African elephant adults weigh from 4,700 to 6,048 kilograms. Because they must hold all of that weight on their four feet, the tissues of their feet have features that enable compression to absorb and distribute forces.

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Plants

Phylum Plantae (“plants”): Angiosperms, gymnosperms, green algae, and more

Plants have evolved by using special structures within their cells to harness energy directly from sunlight. There are currently over 350,000 known species of plants which include angiosperms (flowering trees and plants), gymnosperms (conifers, Gingkos, and others), ferns, hornworts, liverworts, mosses, and green algae. While most get energy through the process of photosynthesis, some are partially carnivores, feeding on the bodies of insects, and others are plant parasites, feeding entirely off of other plants. Plants reproduce through fruits, seeds, spores, and even asexually. They evolved around 500 million years ago and can now be found on every continent worldwide.

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Collenchyma cells in vascular plants support growing parts due to flexible cellulosic walls, which lignify once growth has ceased.

“In addition to the ‘mechanical’ cells – fibres and lignified parenchyma – a third cell type has mechanical functions. This is collenchyma. Collenchyma cells have walls which during their development and extension are mainly cellulosic. They grow with the surrounding tissue as it expands or lengthens. They are more flexible than fibres, and if they remain unlignified, as they might in association with leaf veins or midribs, or in leaf stalks (petioles), they allow for a high degree of flexibility in the organ itself. Often, after growth in length of stems has occurred, and more mechanical rigidity is an advantage, we find that the collenchyma cells become lignified, and function more as fibres.” (Cutler 2005:105)

Last Updated July 26, 2017

References

Book section

Design in plants

In: Nature and Design. Collins, MW; Atherton, MA; Bryant, JA, editors. pp. 95-124. WIT Press. | 01/01/2005 | Cutler DF

“It is the main supporting tissue of growing organs with walls thickening during and after elongation. In older organs, collenchyma may become more rigid due to changes in cell wall composition or may undergo sclerification through lignification of newly deposited cell wall material.” (Leroux 2012:1083)

“Flexibility of collenchymatous tissues is an advantage for any plant part that is subjected to mechanical stress that would result in damaging its tissues.” (Leroux 2012:1095)

Journal article

Collenchyma: a versatile mechanical tissue with dynamic cell walls

Annals of Botany | 29/08/2012 | Leroux O

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