Date: Wed, 10 May 2000 14:17:24 +1000 From: ix@dynamite.com.au To: cp@opus.hpl.hp.com Message-Id: <aabcdefg1462$foo@default> Subject: CP origin
To everyone,
I Hope not to tread on learned toes.
(1) Plants absorb nutrients through their leaves.
Leaves have hairs & glands to keep off herbivores.
If a herbivore gets caught on the hairs or glands & dies, the plant would
absorb some of the ensuing nutrients.
(2) Plants absorb nutrients through their roots.
Roots DON'T have glands or hairs to keep off herbivores.
If the soil is inhospitable, roots do not absorb much in the way of nutrients.
The result: A plant growing in inhospitable soil which can trap insects
would have access to more nutrients.
You all know that there are several different mechanisms of CP trapping.
There is glue, as described above, as used by Drosera, Pinguicula. There
are pitfalls, as used by Sarracenia, Nepenthes. There are man-traps, as
Dionaea, Utricularia.
The origins of the first two groups are obvious - there are many plants
which trap insects on their leaves, and many others that have water-filled
pitfalls (I have personal experience with Dipsacus, the european "teasel",
Brussels sprouts, & Gunnera). Of course, it can be argued that these are
not true carnivores as they do not have their own digestive enzymes, to
which the obvious answer is "Do cows eat grass?" {what I mean is, cows'
enzymes don't digest much grass, it is bacteria in their rumen}. And we
can take that further perhaps by saying that Bromeliads could be
herbivorous (digesting the dead plant material in their vase?).
The origin of seemingly complex organs like fly-traps or bladderworts is I
assume just an extension of rolling up a leaf after it has caught something
- if it can catch something else without unrolling, so much the better.
The origin of carnivorous plants surely happened at about the same time
insects became abundant. I would imagine this would pre-date flowering
plants. I raise the question, how about monocot or gymnosperm or
pteridophyte CPs?
Allen
This archive was generated by hypermail 2b30 : Tue Jan 02 2001 - 17:35:08 PST