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Dark foliage
David E. Ross wrote:
On 8/8/13 8:19 PM, 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. 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. 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. David In the August 2013 issue of Scientific American, the article "The Surprising Origins of Life's Complexity" suggests that evolution strongly depends, not so much on mutations that are advantageous, but more on mutations that are neutral. As such mutations accumulate in the gene pool, their combination eventually leads to changes in an organism. See http://www.scientificamerican.com/article.cfm?id=the-surprising-origins-of-evolutionary-complexity. This application of complexity theory is not universally accepted. No matter the point that I was trying to make, that the outcomes of evolution are limited by the availablity of pathways from the previous situation to a new one remains. Whether this postulated mechanism opens up more pathways that permit greater leaps from one state to another remains to be seen, as does how often it might occur. D D |
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