Leaves Protect From the Elements

snow piles on top of blue green needles of a pine tree

Biological Strategy

AskNature Team

Image: Ryan Arnst / Unsplash / Free non-commercial use

Protect From Loss of Liquids

Water is essential to life. Liquids, mostly water, make up 70 to 90% of all living systems, and the loss of even a small percentage can mean the difference between life and death. Living systems must maintain a proper liquid balance, which is especially difficult in dry conditions. To do so, they must control the movement of liquids across their boundaries. Living systems do this using structures or waterproof materials to prevent or slow liquid movement. For example, when humans receive a cut, they must limit blood loss. Scattered throughout the bloodstream are lens-shaped structures that serve to plug the wound.

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Protect From Temperature

Many living systems function best within specific temperature ranges. Temperatures higher or lower than that range can negatively impact a living system’s physiological or chemical processes, and damage its exterior or interior. Living systems must manage high or low temperatures using minimal energy, which often requires controlling responses along incremental temperature changes. To do so, living systems use a variety of strategies, such as avoiding high or low temperatures, removing excess heat, and holding heat in. Insulation is a well-known example of managing low temperatures by retaining heat using thick layers of hair, fur, or feathers to hold warm air next to the skin.

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Conifers and Others (Pines, Spruce, Gingko)

Clade Gymnosperms (“naked seeds“): Conifers, cycads, Gingko, gnetophytes

There are approximately 1,000 known species of Gymnosperms. These include well known needle-bearing plants like pines, firs, and spruce, as well as some with broad leaves like the Gingko and the gnetophytes. Instead of flowers, gymnosperms produce unenclosed (“naked”)seeds exposed on the surface of cone scales. Economically, conifers make up 45 percent of the world’s lumber production. The first gymnosperms evolved over 390 million years ago in the Paleozoic Era and dominated landscapes for a quarter of a billion years before the evolution and diversification of flowering plants.

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The leaves of conifers protect from drought, snow and cold by employing unique design elements, including a needle shape, thick waxy rinds, and pores set in deep grooves in the needles.

Image: High Contrast / Wikimedia commons /

New shoots of Abies nordmanniana

Image: USDA-NRCS PLANTS Database / Herman, D.E. et al. / Wikimedia commons /

White fir (Abies concolor) leaves

Image: Crusier / Wikimedia commons /

Image: Alan D. Wilson /

Pine Branch Rime, Mackie Road, Coldstream, British Columbia, 7 February, 2012

“Some species of tree, even outside the balmy climates of the tropics, manage to produce a kind of leaf that can survive both drought and cold. Conifers do so. Many of them grow branches that, instead of rising upwards towards the sky, slope gently downwards. In consequence, snow tends to slide off them and does not accumulate into huge loads that might break them. Their leaves are not flat and broad but needle-shaped. They have a thick waxy rind, very little freezable sap, and pores that are set in the bottom of a deep groove running the length of the needle.” (Attenborough 1995:88-89)

Last Updated August 18, 2016

References

Book

The Private Life of Plants

21/08/1995 | David Attenborough

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