Lignified Parenchyma Cells Provide Strength

a microscopic image shows the cells of a cross section of tilia, appearing as a dark blue outer circle, three lighter rings, and a center of blue and burgundy cells

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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Parenchyma cells in plants provide mechanical support when they become lignified and thick-walled.

Helical Wound Fibres Increase Toughness

Plants

Cellulose fibers in plant stems increase toughness by winding around tubes at an angle

“Sometimes axially elongated cells of the ‘packing’ tissue, parenchyma, become thick-walled and lignified. These have similar functions to fibres, but their ends tend not to be pointed. Often no distinction is made between this cell type and true fibres. Cells of this type make up the bulk of the strengthening tissue in bamboos. They are arranged towards the periphery of the stem, the centre of which is often hollow, with transverse septa at intervals.” (Cutler 2005:103)

Last Updated August 18, 2016

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