Is it true that the heat from a fire will germinate the seed
of a redwood tree?
Since I live in Australia I know almost nothing about redwood trees,
except that they are BIG.
I do know about Australian Trees though.
Fire is a part of the environment that many Australian plants have to
deal with. As a consequence of this there are many Australian plants
whose seeds will only germinate after a fire.
The Banksia produces its seeds in a seed pod that is so hard that only
the heat from a bush fire is enough to open the pod and release the
seeds, but they are not released during the fire, but several hours
after. The fire scorches the outer coating of the seed pod, and then
several hours later the slits in the pod will open to allow the seeds
to fall out. This is a useful strategy for the plant, as it allows the
seeds to germinate in soil that has is clear of competing bushes, and
which has just been enriched with a layer of nutrient in the form of
plant ash. Perfect for a seed to get started.
Other plants, such as the Sturt Desert Pea produce seeds which have a
very hard outer coating. This can be softened by several days of
soaking in water, such as might occur in a flood, or by scorching,
such as during a bush fire. The best condition for the Sturt Desert
Pea is to have a fire followed by rain, and then you can see hundreds
of acres of desert turn into a garden of flowers. A spectacular sight.
For more information look up the names of some Australian Plants on
Google - Try Banksia, Sturt Desert Pea, Acacia, Wattle, Bottlebrush,
Melaleuca Callistomen and Eucalyptus.
The seeds are freed when the cone dries out due to heat from fire or insect damage:
Anthony R. Brach, Ph.D.
Many tree species have very thick seed coats on their seeds. These seeds fall
from the parent plant in the vicinity of that parent plant. If every seed
germinated, they would be competing for light, space, water, etc. Better to
hang out in a dormant state until there is no competition any more. When there
is a forest fire, the parents are killed and the seed coats are burned off,
allowing the seeds to finally germinate. Now they have little competition.
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Update: June 2012