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Dark foliage
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 |
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