Waxy Coating Protects From Heat and Drought

bright green euphorbia is seen in sunlight

Biological Strategy

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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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Flowering Plants

Clade Angiosperms (“receptacle seed”): Dandelions, oaks, grasses, cacti, apples

With 416 families containing some 300,000 known species, angiosperms are the most diverse group of plants, and they can be found around the globe in a wide variety of habitats. They are characterized by seeds that grow enclosed in ovaries, which are enclosed in flowers. The floral organs then develop into fruits of myriad kinds and dimensions, from simple seed casings on maples to elaborate fleshy growths like papayas. The oldest flower known from fossils, Montsechia vidalii, appeared during the Jurassic Period 130 million years ago. They are the primary food source for herbivorous animals, which in turn makes them the indirect food source for carnivores as well.

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The stems of euphorbias protect from heat and drought via their hard waxy surface.

Image: Qwertzy2 /

“On the ground around them grow numerous fat, spiny leafless plants that any non-botanist could be forgiven for calling — without hesitation and even perhaps a certain amount of pride in his expertise — cacti. Only if they are in flower might you suspect that they are not. Then a botanist would notice that the numbers of petals and anthers are quite different from those of cacti. These are euphorbias, members of one of the largest of all families of flowering plants with over seven thousand species. In Europe, its common representatives are dog’s mercury and spurge. In South America, euphorbias grow into trees and shrubs, among them the rubber tree and the manioc plant. In African forests, its members include the castor oil bush. And in African deserts they become cacti look-alikes…The cactus family is, in fact, exclusively American, with hundreds of different species growing in deserts from Canada to Chile. The reason that members of these two families resemble one another so closely is that similar conditions of heat and drought have stimulated the same physical response. Both abandon their leaves at an early stage, since these inevitably lose a great deal of water, and both carry out their under the hard waxy surface of their stems which are green with . Both store water in a bloated pillar-like trunk. And both defend that water from robbers by armouring their trunks with sharp spines.” (Attenborough 1995:272-275)

Last Updated October 25, 2016

References

“On the ground around them grow numerous fat, spiny leafless plants that any non-botanist could be forgiven for calling — without hesitation and even perhaps a certain amount of pride in his expertise — cacti. Only if they are in flower might you suspect that they are not. Then a botanist would notice that the numbers of petals and anthers are quite different from those of cacti. These are euphorbias, members of one of the largest of all families of flowering plants with over seven thousand species. In Europe, its common representatives are dog’s mercury and spurge. In South America, euphorbias grow into trees and shrubs, among them the rubber tree and the manioc plant. In African forests, its members include the castor oil bush. And in African deserts they become cacti look-alikes…The cactus family is, in fact, exclusively American, with hundreds of different species growing in deserts from Canada to Chile. The reason that members of these two families resemble one another so closely is that similar conditions of heat and drought have stimulated the same physical response. Both abandon their leaves at an early stage, since these inevitably lose a great deal of water, and both carry out their photosynthesis under the hard waxy surface of their stems which are green with chlorophyll. Both store water in a bloated pillar-like trunk. And both defend that water from robbers by armouring their trunks with sharp spines.” (Attenborough 1995:272-275)

Book

The Private Life of Plants

21/08/1995 | David Attenborough

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