HERB - acorns

[Kathleen Keeler]

Gaylin Walli wrote:

> Isn't
> it true that when trees are under stress they often produce
> bumper crops of the mechanism that makes more trees
> grow? Our maple trees under stress (drought stress, most
> notably) produce far more whirlygigs than when they're
> happy and well fed.

Some plants flower under stress, as Jasmine said, "I'm dying, I'd better
reproduce"
But others won't flower unless they are doing very well.

Its the sort of thing that would get me a very nice professional publication if
I saw a pattern and documented it.  So I'll give you  hand waving because I
haven't read anything that makes sense of it.  I think it depends on the
environment the plant evolved in.  If stress was a recurring thing in the
environment and those that
got seeds off had seedlings when the stress ended, it'd be a  common response.
Or if the plant "knew" it was dying (as in the root damage) and so put all its
energy into seeds instead of storing some for next spring. But if those who
used lots of energy to flower just died and had no more seedlings than those
who saved their energy, they wouldn't respond to stress by flowering. (Some
places the seed would rot rather than germinate, or animals would eat it 100%
for reasons that seeds can be poor risks).  Also in some environments or plants
it might not be possible to make seeds fast enough to use it as a stress
response -- for example a lot of the bigger-acorn oaks (black oaks) and some
pines take 2 years to mature a seed -- hard to be responsive with that kind of
seed production. Or if the pollinators are seasonal (hummingbirds in Arizona
and Colorado) but the stress was at some other time, flowering wouldn't do
anything at all.

Whatever the explanation, stress induces flowering in some species, delays it
in others, changes nothing in still others.

There are many things in which what you can say about plants is "wow! how
diverse!" which of course
is not nearly as satisfying as saying "yes, they all [whatever] because ..."
Seed germination
for example:  in the dark, in the light, after a chilled period, no chilling
needed, after a particular time,
no wait required...or flower color "red, orange, yellow, blue, purple, green,
ultraviolet, violet, brown, white..." in groups of "1, 2, 3...many" which open
"from the top, from the bottom, from the top of individual clusters but from
the bottom of the stem, from the middle, upward on the first flower stalk but
downward on any secondary ones..."  And tho people make patterns out of it
(hummingbird pollinated flowers are red, bee-pollinated flowers are yellow,
blue and purple) the plants don't care about our need for order and there are
exceptions all over the place.

Agnes
kkeeler1 at unl.edu

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