first leaves of plants-- thought of as evol.vestiges or fetus-differences
On Fri, 23 May 2003 01:29:15 -0500, Archimedes Plutonium
wrote: I have made the observation that most every plant when it shoots from its seed with its first leaves, that these first leaves are rarely (perhaps never) the same as what all the other leaves of this plant matures into. Would it not save the plant some energy in its early growing if all the leaves were the same from birth to maturity? Anyway, does anyone know if any plant exists wherein its first leaves are no different from any other of its leaves? And the question I am mostly interested in is whether these first leaf are an evolutionary vestiges such as human vestiges of gill slits. So are these first leaves vestiges of all plants that can be traced back to some ancestral first plant. Or, instead of being evolutionary vestiges, are the first leaves different from later leaves as in animals the fetus is different from the later growing animal. What I am trying to reconcile in thought is why would a plant invest energy in its first leaves of leaves that are very much different from all later leaves, when it probably would be better for the plant if all of its leaves during its entire lifetime were one and the same type of leaf. Archimedes Plutonium, whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies oh my GAWD.... cotyledon look it up |
first leaves of plants-- thought of as evol.vestiges or fetus-differences
Archimedes Plutonium wrote in message ...
I have made the observation that most every plant when it shoots from its seed with its first leaves, that these first leaves are rarely (perhaps never) the same as what all the other leaves of this plant matures into. Would it not save the plant some energy in its early growing if all the leaves were the same from birth to maturity? Anyway, does anyone know if any plant exists wherein its first leaves are no different from any other of its leaves? And the question I am mostly interested in is whether these first leaf are an evolutionary vestiges such as human vestiges of gill slits. So are these first leaves vestiges of all plants that can be traced back to some ancestral first plant. Or, instead of being evolutionary vestiges, are the first leaves different from later leaves as in animals the fetus is different from the later growing animal. What I am trying to reconcile in thought is why would a plant invest energy in its first leaves of leaves that are very much different from all later leaves, when it probably would be better for the plant if all of its leaves during its entire lifetime were one and the same type of leaf. While others omg each other to make themselves feel better about being jerks, I see that some of your question have still been left unanswered. One concerns the evolutionary homologies of the cotyledons, ie. can cotyledon shape be used for phylogenetic relationships. Unfortunately, the "ontogeny recapitulates phylogeny" pattern found in animals does not apply anywhere near as well in plants. This is particularly true after the seed is formed, were much separation of form has alreadt occurred. The cotyledon's shape can be fairly similar across several species of a genera, but it rarely keeps this similarity over genera. This is because the duties of the cotyledon often must be structured to particular environments. However, the cotyledon's role does have a fairly large evolutionary history in the vascular plants. It was a necessary adaptation to support plant growth through to the phase where it can produce enough food on its own by photosynthesis. In fact, the number of them (1 or 2) separates two major evolutionary forms of the vascular plants, the monocots and the dicots. |
first leaves of plants-- thought of as evol.vestiges or fetus-differences
galathaea schreef
In fact, the number of them (1 or 2) separates two major evolutionary forms of the vascular plants, the monocots and the dicots. + + + And back to the Stone Age we go (again)! PvR |
first leaves of plants-- thought of as evol.vestiges or fetus-differences
On Mon, 26 May 2003 06:54:07 GMT, "P van Rijckevorsel"
wrote: galathaea schreef In fact, the number of them (1 or 2) separates two major evolutionary forms of the vascular plants, the monocots and the dicots. + + + And back to the Stone Age we go (again)! PvR I am curious as to what you mean by that PvR? Is it that the concept above is no longer considered correct, or the fact that trying to tell plutonium something is like starting at the bottom? |
first leaves of plants-- thought of as evol.vestiges or fetus-differences
"P van Rijckevorsel" wrote in message .. .
galathaea schreef In fact, the number of them (1 or 2) separates two major evolutionary forms of the vascular plants, the monocots and the dicots. + + + And back to the Stone Age we go (again)! PvR You are absolutely correct in noting that the distinction is not an absolute phylogenetic one (which has been noted for some time). There are certainly plants with two cotyledons which more properly should be systematically related with the monocots and vice versa. These relationships underline the true variability of plants, and the fact that dicots are almost definitely not all derived from a common ancestor point to the struggle of classification by form (which has been surpassed by a much more rigorous science with the advent of gene pattern methods). However, I was merely attempting to point out what is still a useful classification of form over large classes of flowering plants. I was, unfortunately, sacrificing rigorousness to ease of exposition to assist the OP in their sudy of these interesting parts of the growth cycle, and I do appologize for not properly qualifying the remark. It is still (I believe!) recognized that the number of cotyledons is a characteristic very often conserved over large histories of evolution, but it is now recognized that there is not merely a single event which has caused this quantity to vary but, indeed, several and likely in both direction (addition and loss of cotyledons). |
first leaves of plants-- thought of as evol.vestiges or fetus-differences
I found my name on Archie's killfile. I feel honored to listed in his Who's
Who!!! Archie's list is so long, if he keeps on going, he will have the name of everybody on the internet!!! Archie isn't just a deranged idiot, he's a pompous fool too!!! Archimedes Plutonium wrote in message ... 25 May 2003 21:13:19 -0700 galathaea wrote: (snipped what I wrote) While others omg each other to make themselves feel better about being jerks, I see that some of your question have still been left Well, my killfile has been greatly effective for the past many years and you are welcome to copy and use it. I waste none of my time on anything they write. http://www.archimedesplutonium.com/M...llfiledom.html unanswered. One concerns the evolutionary homologies of the cotyledons, ie. can cotyledon shape be used for phylogenetic relationships. Unfortunately, the "ontogeny recapitulates phylogeny" Not exactly sure of what that means, or is trying to convey. I brought in the subject of animals and vestigial evolutionary form such as the example of gill slits in humans because it appears that most first leaves of plants look about the same and are very different from the later mature leaves of those plants. So one of my questions was whether these first leaves have some better energy capture of photosynthesis that later mature leaves lack in quality of photosynthesis capture. Sort of like the idea that a beginner child of bicycle uses trainer wheels before going solo. So are these cotyledon first leaves superior to later leaves? Or would any and all plants be better off if there first leaves were noncotyledon and were exactly like all the other later mature leaves? If so would suggest that cotyledon leaves are evolutionary vestiges just as gill slits in humans are evolutionary vestiges and although they act as the first photosynthesis of the plant, they are inferior to the photosynthesis if these first leaves were not cotyledon but rather instead what the future mature leaves are. I doubt any scientist has researched whether a cotyledon first leave is any superior to later leaves. My guess at this time is that they are inferior in photosynthesis because they are evolutionary remnants of the gene coding just like gill slits are remnants of nonfunction. I would guess if there were a means of testing whether a later leaf is superior in photosynthesis to a cotyledon leaf that such would be the case. That is a guess. A guessed based on the idea that animals have remnants that the gene code cannot seem to get rid of and that the cotyledon first leaves were the aeons ago leaves like gill slits in humans. Can you think of a means of testing whether a cotyledon leaf is superior or inferior in photosynthesis to a later mature leaf? I cannot not at this moment but I am unfamilar with the literature and methods of botany to do such a test. Perhaps someone has already found a means of doing that test. I have a baby pear true at this very moment coming from seed. It had a cotyledon first leaves and now it has 2 new leaves of what a pear leaf really is. So I wonder if a means of testing the photosynthesis of the cotyledon leaf of pear and then the photosynthesis ability of the next 2 leaves of that pear is. pattern found in animals does not apply anywhere near as well in plants. This is particularly true after the seed is formed, were much separation of form has alreadt occurred. The cotyledon's shape can be fairly similar across several species of a genera, but it rarely keeps this similarity over genera. This is because the duties of the Yes, my pinenut trees seem to have the same first leaves as later mature leaves of that pine. But I wonder if any pine or spruce or evergreen has a cotyledon that looks more like a pear cotyledon than mature pine leaves. I wonder if we trace all cotyledon leaves of all plants whether that track leads to the evolutionary history of the past to common ancestors. Perhaps the gene coding of all plants of the genetic region that does the cotyledon maybe a marker of the history of all plant species, that we can tell which species is ancestral to another. cotyledon often must be structured to particular environments. Well if that is the case then it sinks the idea that cotyledon is an evolutionary remnant. Perhaps a fractional or percentage adaption because most cotyledons are fairly similar. So that environment has not played much of a role. However, the cotyledon's role does have a fairly large evolutionary history in the vascular plants. It was a necessary adaptation to You know how blood is often compared between species to find out if one is ancestral to the other. Perhaps cotyledon variations is a marker in plants to tell if one is ancestral to another. support plant growth through to the phase where it can produce enough food on its own by photosynthesis. In fact, the number of them (1 or Yes, but that is the important question for me to find out. I want to know if cotyledon leaves are superior in anyway to later leaves. I would guess they are inferior because they are evolutionary vestiges like gill slits in humans that the gene code could not get rid of totally. I would guess that if plants could have a choice of their first leaves being cotyledon or being what later mature leaves are that all plants would forego the cotyledon stage and have all of its leaves, the very first ones all be what the later mature leaves look like. This guess is based on the presumption that later leaves of a plant species are its most efficient photosynthethic leaves. And that the first leaves of cotyledon are like a dumpsite of ancient genetics of that plant, just as human embryos get rid of its gill slit during the embryo stage. 2) separates two major evolutionary forms of the vascular plants, the monocots and the dicots. I bet if all plants had their choice, they would choice having all their leaves from their first to their last as all the same and that the cotyledon stage of a plant is the getting rid of ancient genetics that are there. I would need some reliable experimental method to test whether cotyledon leaves are superior or inferior to later leaves. Such a method probably does not exist yet. Archimedes Plutonium, whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies |
first leaves of plants-- thought of as evol.vestiges or fetus-differences
The concept has long been obsolete, Buckwheat.
The true situation is much more complex than that. Its a waste of time trying to explain anything to Archie because he's too far gone and never listens anyway. Archie always thinks he making some profound discovery when, in fact, he is always making a total ass of himself. He never does his own research. You efforts are better spent doing something constructive rather than trying to teach the unteachable. Archie is not worth the "hand holding" he craves. d buebly wrote in message ... On Mon, 26 May 2003 06:54:07 GMT, "P van Rijckevorsel" wrote: galathaea schreef In fact, the number of them (1 or 2) separates two major evolutionary forms of the vascular plants, the monocots and the dicots. + + + And back to the Stone Age we go (again)! PvR I am curious as to what you mean by that PvR? Is it that the concept above is no longer considered correct, or the fact that trying to tell plutonium something is like starting at the bottom? |
first leaves of plants-- thought of as evol.vestiges or fetus-differences
And back to the Stone Age we go (again)!
PvR galathaea schreef There are certainly plants with two cotyledons which more properly should be systematically related with the monocots and vice versa. + + + IIRC monocots have 0-2 cotyledons and dicots 2-6. The idea of dicots as a natural group is being abandoned. It may be that the eudicots do have always two cotyledons, I would have to check. + + + However, I was merely attempting to point out what is still a useful classification of form over large classes of flowering plants. + + + There are other more useful characters PvR |
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