Compacted Leaves Form Efficient Heat Insulation

close up photograph of tree leaves and trunk during the day

Biological Strategy

Grass tree

AskNature Team

Image: Cerlin Ng / Flickr / Some rights reserved

Protect From Fire

Depending on location, fire can be either predictable or unpredictable. In some areas, fires occur in cycles ranging from annual to hundreds of years. Where fire is cyclic, living systems must be able to not only survive fire, but to quickly recover following it. For example, pine trees that live in areas with periodic fires have thick bark that provides insulation, thereby protecting the tree’s living tissue.

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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 leaves of the grass tree serve as efficient heat insulation via compacted arrangement of leaf bases.

Image: Captain Chaos /

At MacKenzie Falls in the Grampians, a beautiful National Park in Victoria, Australia. These plants are called grass trees. Apparently they only put out the long shoots at their tops in times of stress, such as in this case the huge fire which had swept through the Grampians a year earlier.

Image: yewenyi /

This image shows the grass tree with its leaves forming protection from possible fire.

“This country [southwestern Australia] is also one of the headquarters of the grass tree…It is neither a grass nor is it a tree. It is a distant relative of the lilies. But it does have very long narrow leaves that resemble grass, and they are born in a great shock on the top of a stem that looks like the trunk of a tree and may be up to ten feet high. However the core of this trunk is not timber but fibre and what seems to be bark is, in fact, the tightly compacted bases of the leaves which are shed annually from beneath the crown as the plant grows higher. These bases are glued together by a copious flow of gum and they form a very efficient heat insulation. Since the plant sheds one ring of leaves annually, counting the rings of bases in this fire-proof jacket gives an indication of age and reveals that the grass trees not only grow only a foot or so in a decade but that a mature one may be about five hundred years old and therefore be the survivor of dozens of fires.” (Attenborough 1995:190-191)