Burning Stimulates Flowering

landscape photograph of a blue sky and trees next to a dirt road

Biological Strategy

Grass tree

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Regulate Reproduction or Growth

Reproduction and growth are two physiological processes that occur in all living systems. There are situations when conditions are right for both, and other situations when continuing either harms the living system because both have a very high energy cost. Reproduction and growth are unique in that both can stop until conditions improve, although stopping either for an extended time can cause problems. An example of regulating reproduction is a process called delayed implantation or embryonic diapause found in some mammals, such as otters. An otter’s embryos sometimes temporarily cease developing and won’t develop further until the female senses that conditions are suitable.

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Send Chemical Signals (Odor, Taste, Etc.)

Tastes, odors, and hormones are all chemical signals that can float through the air or water, or be applied to solid surfaces. Chemicals are important for signaling and communication; even humans, with our underdeveloped sense of smell, are influenced by chemicals more than we realize. Chemical signals are often specific to the living system intended to receive them, and are often relatively weak, dispersing upon moving through liquids or gases. To ensure that chemical signals reach their target, living systems create unique chemical signals and methods of dispersal. One example is an orchid that is pollinated by dung beetles, and therefore distributes a dung-smelling aroma to attract them.

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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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Flowering of grass trees following a fire may be triggered by a huge release of ethylene gas as the trees burn.

“When the flames do come, they quickly burn off the great tuft of leaves [of the grass tree] which incinerate almost instantaneously in a shower of red sparks that fly high into the sky. But the stem, surrounded by its fire-guard remains unharmed and the leaves are quickly regrown. The fire, however, has an additional effect that initially is invisible. As all the vegetation goes up in flames, great quantities of ethylene gas are released. This permeates to the heart of the grass trees and causes a major change within them. A few months after the fire has passed and the leaves have regrown, a vertical green rod emerges from the centre of the leaves. It grows taller and taller until it may double the plant’s height. Then, along its length emerge a multitude of tiny white flowers. It may be the production of ethylene on a vast scale following the fire that cues the flowering of almost all the adult grass trees in the bushland.” (Attenborough 1995:191)

Last Updated August 18, 2016

References

Book

The Private Life of Plants

BBC Books | 21/08/1995 | David Attenborough

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