"wcb" wrote in message
...
Elaine Jackson wrote:

From what I understand (to save time let's agree that this qualification
applies to all of what follows), there are certain plants that have a
finite lifespan built into them: they go to seed and then they die.
(Incidental question: does such a lifespan always coincide with a single
solar year?)

Because these sorts of plants are seed oriented.
all they aim to do is produce a crop of viable seed.
Not all coincide with one year, annuals do, biannuals
will go two years, produce seed and die



Then there are animals, who have decrepitude built into them
instead: it can't be put off indefinitely, and once it starts, it
continues until the animal is too feeble to survive.

Please comment on anything that's incorrect so far.

My main question is: What about trees? I can't recall ever hearing of a
tree that died of old age.


Many do, Many trees are not that long lived, a
lot of trash trees are sold in nurseries for landscaping.
Trees that grow fast, but won't last. Arizona ash for instance.
Some trees do have long, but distinct life spans,
A few may life quite a long span, olives, bristlecone
pines, but only a relative few species will have such a long
life before them.



They continue growing throughout their lives,
but is there anything about perpetual growth that necessarily leads to
death? (Incidental question: How does a tree's growth rate change over
the
course of its life?)


Depends on the species. Any number do have distinct
life cycles. They grow fast when young, slow down in middle age,
and may spread a bit in old age but don't grow noticably
taller. And many trees do have distinct lifespans,
some may go 100 - 150 years and decline. Some fast
growing pines may not get 50 years.




Obviously something will get them eventually, just
because life is a gamble and every lucky streak has to end. But, in
principle, could a tree live forever?

Bristlecone pines are known thousands of years old,
possibly they may go on forever until accident,
or change of their habitat ends their lives.










Any help greatly appreciated.

Peace

--
Dance, monkeys, dance!

Cheerful Charlie


If human beings could find the fountain of youth, then their lifespan would
be about 10000years average because some accident would take them out.
Maybe:
1/ Falling out of a tree.
2/ Falling off a cliff.
2a/ Falling off a horse.
3/ Overdosing on cascara.
4/ Run over by a train.
5/ Being hit by a meteor.
6/ Succumbing to some loathsome disease.
7/ etc ad nauseam.