Are there "Identical Twin" plants?

glen yakimoff gleyakim at hotmail.com
Tue Dec 19 06:22:26 EST 2000


Just a footnote/clarification, I get the impression that somebody out there
thinks that plants borne by "spore producing plants" are asexually cloned
plants. Whilst spore producing plants can produce "clones" asexually through
rhyzome roots that may subsequently be severed, or by other forms of
division, etc..........:- Spores actually have sexual parts, where a male
sperm can be released and swim (through moisture) to the female part of
another spore producing the first generation of a sexually produced plant
(called the prothallus). (reference "The life cycle of the fern"  p40 from
Australian native plants third edition by wrigley and fagg).
 In other words spore producing plants produce sexually through their spore.
Spore producing plants Include ferns,club mosses, and fork ferns (a
different group to regular ferns).

Cereoid wrote in message <91hd6u$ke5q$1 at newssvr06-en0.news.prodigy.com>...
>Sorry dude but flowering plants produce seeds not spores.
>
>You need to study up on your basic botany then get back to us.
>
>
>"George Hammond" <ghammond at mediaone.net> wrote in message
>news:3A3C13B6.D8241A58 at mediaone.net...
>> Cereoid wrote:
>> >
>> > Sorry but you are mistaken. The "Dandelion" is not an asexually
clonally
>> > propagated species. It reproduces from seeds. Seeds are propagated
>sexually
>> > by definition.
>>
>> GH:  That's what i was asking.. i got the impression Dandelion "seeds"
>>      were actually "spores"... thanks for the info.
>>
>>
>> > An asexually propagated species is one propagated from offsets,
division
>or
>> > tissue culture.
>>
>> GH:  I'm aware of the definition.
>>
>> [Hammond]
>>    Elsewhere you have asked what the BOTTOM LINE of this discussion
>> is.  well, here it is.  Perhaps you can answer the fundamental question
>> which is posed below:
>>
>> > > GH:  You've totally missed the point. I DON'T WANT TO CONTROL
>ANYTHING.
>> > >      What I want to know is, what is the Standard Deviation of plant
>> > >      growth in the "real environment" when we are talking strictly
>about
>> > >      a crop of geneetically identical plants?
>> > >        Now, somebody in agriculture must KNOW the answer to this, say
>> > >      for potatoes, or onions or some other asexual crop plant.
>> >
>> > It depends on the variety and on the trait, and it depends if you are
>talking
>> > about the SD within a field or between fields.  For something like
>flower color,
>> > the SD would be close to zero.
>>
>> GH: Right, I understand that.
>>
>> > For something like height or yield, it would
>> > fairly uniform within a field (barring spots which are overly wet/dry,
>or
>> > otherwise inappropropriate),
>>
>> GH: YES, this is what I'm talking about, "gross overall size",
>>     I'm NOT concerned with "specific traits".
>>       I argue that there is such a thing as a "growth curve" for
>>     ALL plants and animals and the "plateau" of this
>>     curve represents what we call "maturity", or
>>     "terminal growth".
>>       However, there is reason to believe that there is such
>>     a thing as a "theoretical growth curve" for any given
>>     genetic species, and that in fact, since a large cloned
>>     plant population has a "terminal growth variance"; that very
>>     few plants EVER achieve this "theoretical growth curve".
>>       Would you agree with this speculation?
>>
>>  but could be quite large between fields, depending
>> > on how distant they are.  Breeders generally call this genotype x
>environment
>> > interactions.  Genotypes are known which are more stable across
>environments than
>> > others.  In the end, the SD is difficult to predict without measuring
>it.
>>
>> GH:  Yes, it is the "between fields" VARIANCE that I am talking about.
>>      You apparently agree that such a thing exists and can be
>>      measured.
>>
>> >
>> > Keep in mind that plants need not reproduce vegetatively to be
>genetically
>> > identical.  Hybrids from inbred parents (as in a field of corn) are
>genetically
>> > identical.  So are inbred plants (as in a field of soybean) and
>apomictic plants
>> > (as in dandelions).
>>
>> GH:    You see; the question here is nothing but the old NATURE-NURTURE
>>      discussion.... with a NEW TWIST.
>>        It is now hypothesized that higher animals, and probably plants,
>>      have something which we could call a "nominal maximum genetic
>>      size", and that in the natural environment, very few IF ANY
>>      individual specimens EVER ACHIEVE IT.
>>        The object then, becomes the task of PROVING THIS CONJECTURE.
>>      That is, proving from existing data, that there is such a
>>      thing as a "terminal growth deficit" that exists for all
>>      plants and animals, and naturally we would want to eliminate
>>      "genetic variation" from the measurements, which is why the
>>      question has come up explicitly concerning "clonal" plants.
>>
>>
>> --
>> BE SURE TO VISIT MY WEBSITE, BELOW:
>> -----------------------------------------------------------
>> George Hammond, M.S. Physics
>> Email:    ghammond at mediaone.net
>> Website:  http://people.ne.mediaone.net/ghammond/index.html
>> -----------------------------------------------------------
>
>







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