GardenBanter.co.uk - View Single Post

24-09-2003, 03:02 PM

[P van Rijckevorsel] wrote...
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.

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

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.

+ + +
This is just an isolated example, which does not prove much either way.
Certainly an internal site in Ficus carica would be BIG NEWS.
+ + +

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].

+ + +
Agreed, the Ice Ages are just a red herring here.
I liked their effect on ferns, but that is an isolated case too
+ + +

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?]

+ + +
Wouldn't know, but I'd guess that under those circumstances water will be
the limiting factor. Those circumstances will give interesting growth forms
and adaptations (like greenhouse plants), but nitrogen fixation should be
nowhere near the top of the list?
PvR