Jeff Layman wrote:
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.

I see no evidence of either of those statements.

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 saying they regressed (went backwards) you are saying there is a
particular direction that is "right". It ain't so.

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! :-)

OK

D