Roots Maximize Water Uptake

a tree with white bark has roots growing over bright green grass

Biological Strategy

Plants

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Capture, Absorb, or Filter Liquids

The most common liquid used by living systems is water, which they require to survive. But there are many other liquids that provide nourishment, play a role in defense mechanisms, or serve other purposes. Water varies in its availability; it is sometimes plentiful and sometimes very scarce or only available as fog or mist. To minimize the energy required to capture, absorb, or filter liquids, living systems have strategies that take advantage of the unique properties of the given liquid. For example, water moves from a gaseous to liquid state when it encounters a surface colder than the air. Plants in forests that experience fog and clouds more than rain have strategies that condense liquid water from moist air.

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Optimize Shape/Materials

Resources are limited and the simple act of retaining them requires resources, especially energy. Living systems must constantly balance the value of resources obtained with the costs of resources expended; failure to do so can result in death or prevent reproduction. Living systems therefore optimize, rather than maximize, resource use. Optimizing shape ultimately optimizes materials and energy. An example of such optimization can be seen in the dolphin’s body shape. It’s streamlined to reduce drag in the water due to an optimal ratio of length to diameter, as well as features on its surface that lie flat, reducing turbulence.

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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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Roots of plants maximize water uptake by adapting their orientation to the environment.

Image: Stephen J. Salter /

Image: Aaron Escobar /

This photo shows both the above and below ground structures that are important for transpiration and movement of water.

“To find water, a plant has to position its roots with just as much precision as it arranges its leaves. If moisture is in very short supply, then a plant may have to drive a tap root deep into the ground to reach the water table. Some desert plants have had to develop root systems that are far deeper than they are tall and extend laterally a very long way beyond the furthest extent of their foliage. Even if the environment is well-watered, a plant may still need to compete with others for this essential commodity, so it positions a network of roots within a few inches of the soil surface, where it can gather the rain water before others can.” (Attenborough 1995:48-51)

Last Updated October 7, 2016

References

Book

The Private Life of Plants

21/08/1995 | David Attenborough

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