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23-09-2003, 11:08 PM

In article ,
[P van Rijckevorsel] wrote...

That is what I was told by a botany professor.

mel turner schreef
Okay, but even botany professors may make mistakes. I suspect that
this was just an error.

+ + +
I am uneasy. I will admit to having heard botany professors making erroneous
statements, when talking outside their own field. However I have also heard
botany professors making statements that seemed unbelievable, but did check
out.

Sure, and I'd be glad if this is yet another case where I get to
learn something new and surprising.

+ + +
Where inside the plant are the blue-greens supposed to live?

In the leaves.

+ + +
Are you sure that he meant inside the leaves, or could he have meant in some
exterior feature of the leaves?

Well, there are plants with symbiotic nitrogen-fixing bacteria living
inside of the leaves. I just doubt that this is another example. The
internal site isn't problematic; N-fixing blue-green colonies do form
deep inside massive solid stems of Gunnera species.

+ + +

There are more things in heaven and earth, Horatio, than are met with on
the Web.

Of course.

[...]
Probably at some time during the Ice Age, F.carica hit on this solution
to the problem of a shorter growing season and less light than its fellow
species.

+ + +
No matter what is the case here, the Ice Ages will have nothing to do with
it? Wrong area and wrong timescale.

There is that, but I'd be more interested in the more basic
question of the existence of the phenomenon than in this perhaps
dubious explanation for it [if it doesn't exist, the explanation
is moot]. Still, have shortened growing seasons ever been invoked
before as a major selective pressure for evolving nitrogen-fixing
symbioses? Are they especially prevalent in arctic and high alpine
environments, or in desert ephemerals?]

cheers