Serotiny

  Serotiny is the behaviour of some plant species that retain their non-dormant seeds in a cone or woody fruit for up to several years, but release them after exposure to fire. The cones protect the seeds from granivores and the heat generated by bush fires. However, during a bush fire the heat melts resins in the seed, that once held the cone or fruit tight shut, which then allows the structures to open and release the seeds. Such survival strategies allow for seeds to be released after fires which signal the clearance of competitor plants from the environment.

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Serotinous species are characterised by the possession of an aerial seed bank. Seeds on the ground have a limited life span and are vulnerable to bush fires, whereas in the air the seeds can remain viable for several years and are protected from fires. Fire triggers the release of seeds from these fruits and then they are released into an ash bed resulting from burning of the vegetation. Ash after a fire raises the pH of the soil which can also be a trigger in the germination of serotinous seeds.

Serotinous species that release a small amount of seed spontaneously are referred to as weakly serotinous.

Examples of species that use this method of seed release are species of the genera Conospermum, Pinus and Eucalyptus, the Giant Sequoia and nearly all species in the Proteaceae family .

Serotiny was first described in pine trees in 1880 where cones that did not open were descried as "serotinous cones".^[1] The connection between closed cones and fire was not made until 1977 when J.L. Harper noted that "the evolution of serotiny in pines ensures that seed is stored in cones on the tree and only released to germinate after a fire."^[2]

References

the serotiny is also a characteristic of many desert cacti, that store its seeds inside the mother plant stem.