On 09/08/2013 04:19, David Hare-Scott wrote:
Higgs Boson wrote:
Have often wondered how plants with dark foliage, like the dark red
canna, handle chlorophyll.

Wikipedia has a long article; this is the first graph:

Chlorophyll (also chlorophyl) is a green pigment found in
cyanobacteria and the chloroplasts of algae and plants.[1] Its name
is derived from the Greek words χλωρός, chloros ("green") and φύλλον,
phyllon ("leaf").[2] Chlorophyll is an extremely important
biomolecule, critical in photosynthesis, which allows plants to
absorb energy from light. Chlorophyll absorbs light most strongly in
the blue portion of the electromagnetic spectrum, followed by the red
portion. However, it is a poor absorber of green and near-green
portions of the spectrum, hence the green color of
chlorophyll-containing tissues.[3] Chlorophyll was first isolated by
Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817.[4]

Read the whole thing if interested, and make any
comments...appreciated.

HB

The third section on why chlorophyll is green not black is quite interesting
to me. The explanation given, which I think is widely accepted in the
botanical community, is that some (apparently superior) structures and
functions of living organisms have not been reached by evolution because
there was no evolutionary pathway from where they came from to get there.
This accounts for the less than optimal structure of many aspects of life,
eg the human eye and the giraffe's neck. In fact it is characteristic of a
process that proceeds by many small connected steps to have such inferior
outcomes. A process of design (such as human engineering) can abandon a bad
design and take a completely different approach. Evolution cannot do that.

It's interesting that nature didn't come up with the wheel, one of the
most energy-efficient ways of moving around (or did I read a few years
ago that there was some strange organism which could move like a wheel?
I believe that there are some desert spiders which can escape predators
by pulling themselves into a ball shape and rolling down sand dunes, but
that not really the same thing as a wheel). It's probably because the
moving parts of a wheel are completely separate from each other, and it
would not be possible to repair the revolving part of the wheel if it
was damaged, as it would have no blood supply.

Evolution is undirected and has no 'final' target nor does it look to the
future as an engineer does, it can only work incrementally on choosing which
variation of structure or function is better suited to the environment the
organism is in at that time.

That's not quite true. If it is assumed that life started in the sea,
it should have stayed in that environment, but it didn't. Some animals
changed (evolved?) to make use of land. Even more oddly, some changed
back (eg seals) to make lesser or greater use of their "old"
environment, whilst others, such as dolphins evolved (or should that be
regressed?!) to become totally dependent on their old marine environment.

In case anybody thinks that evolution is too academic or even off topic, I
think it is fair to say that having an understanding of evolution of plants
and organisms that relate to plants (eg predators and symbiots) will make
you a better gardener.

Yes, that's true. There are quite a few examples of parallel evolution
(cacti and other succulents; alpines - particularly the giant lobelias
and puyas) to support that. If you know how to grow cacti - which are
really all New World plants - you will have little trouble if you decide
to grow lithops from South Africa.

And if you find it impossible to grow giant lobelias, you will find it
just as impossible to grow puyas! :-)

--

Jeff