Please enlighten my ignorance 8-)

glen yakimoff gleyakim at hotmail.com
Thu Jan 11 03:39:08 EST 2001


Cereoid wrote in message <93hnb0$6vnm$1 at newssvr05-en0.news.prodigy.com>...
>Whenever one tries to compare the classification of plants with that of
>animals, they will always get themselves into trouble. They are completely
>different systems that follow completely different rules. Plant
>classification is based primarily on the structure of flowers and flower
>parts but differences in vegetative parts often play a role in
>distinguishing closely allied species.
>
>The genus Euphorbia is very large and heterogeneous. All the species in the
>genus share the unique inflorescence called a cyathium. There has been talk
>over the years about recognizing the various subgenera as separate genera.
>Attempts have been made to reinstate Chamaesyce, Tithymalus and Poinsettia
>as genera but they have not been universally accepted. Rather surprisingly,
>the type species for Euphorbia is the arborescent succulent species
>E.antiquorum L. If the genus was divided up, none of the well-known annual
>or perennial species would remain in the genus Euphorbia.
>
>
>"Zebitty" <zebitty at australis.aunz.com> wrote in message
>news:9025C37DBzebittyaustralisaunz at 203.37.234.18...
>> Hi, I'm back from my sojourn to Northern Australia and am a bit more
>prepared
>> now. Thanks for your replies.....and yes I did mean Solanum.
>> Now to address a few issues.....I trained in comparitive and human
>physiology
>> so largely animal taxonomy is not an issue as I am aware of the kingdom
>> structure.......I am however, a botanical taxonomy virgin....so please be
>> gentle 8-)
>>
>> >Yes living creatures in the same species/genus/family usually look
>> >alike, but not always. The Australian Platypus and Echidna are closely
>> >related (ie they are both monotremes) however, superficially, they look
>> >quite different, and inhabit different environments.
>>
>> Monotremata is a famililial relationship.....based on the fact that they
>only
>> have one opening for intestinal and reproductive systems. However, can
one
>be
>> sure that they are truly closely genetically related (I'm not aware of
any
>> studies though I'm sure they exist) or could they both just grouped
>together on
>> that one basic morphological similarity which may or may not be the
result
>of
>> convergent evolution - perhaps all proto-mammals had this arrangement. To
>use
>> another example. The visual pathway of Megachiroptera (flying foxes) is
>very
>> similar to primates (the only other animal that is!!!) so do we conclude
>that
>> primates and megachiroptera are related or is it the result of convergent
>> evolution?

>Glen Hoye (a bat authoriy from Australia), lectures on bats, and has spoken
of how bats are divided into two groups:- microbats (insectivores), and
megabats (bats that take pollen and eat fruit). He said that there are two
theories of how these two groups evolved. One is theory based on the two
groups of bats evolving independantly, with one group evolving from
primates!!!
(the other theory is that the two group evolved from a common anscestry)

>> On a familial level I find much of plant taxonomy perplexing....I was
>finding
>> genus relationships in plants difficult enough to grasp as (this was the
>> original example that I had in mind) Euphorbia millii and Euphorbia
>pulcherrima
>> seem (as far as my limited ability can tell) to have little in common
>apart
>> from the fact that they both have a hydrophobic milky sap. But quite
>obviously
>> a milky sap is a poor commonality as many quite obviously unrelated
>species
>> (ie. Ficus elastica) have milky sap.

Euphorbia spp have very similar stigma and stamen arrangements in their
flowers, and botanist have though of dividing this genus


>>
>> Yet an anteater may
>> >superficially look like an Echidna, but it is not closely related .
>>
>> Personally I don't think they look anything like one another. But that
>could be
>> because I am familiar with animal but not with plant morphology.
>>
>> >Taxonomy is based on features which are often, but not always, based on
>> >genetic chromosomes.
>>
>> Given that much of the taxonomic record was developed before the
discovery
>of
>> the double helix, I would question that assertion!! But if you can
>convince me
>> otherwise I'd be happy to listen.
>>
>> >Are you getting confused between genetics, and what are living creature
>> >looks like?
>>
>> No, I don't think so. Physiology and morphology can be similar or even
the
>same
>> and be unrelated as a result of convergent evolution. And this is my
>> point.....how much of plant taxonomy is actually genetic and how much is
>merely
>> based on strong similarities in certain structures and systems?
>>
>> >
>> >Cereoid wrote in message
>> ><91mb9o$n26o$1 at newssvr06-en0.news.prodigy.com>...
>> >>Dear Zebitty,
>> >>
>> >>Which species in particular that are in the same genus but look
>> >>radically different is it to which you allude?
>> >>
>> >>Species in the same genus typically share certain floral features but
>> >differ
>> >>vegetatively. It may also be true that vegetatively similar plants are
>> >>in different genera.
>> >>
>> >>Then there is the possibility that the plants you have seen are
>> >>misidentified or no longer in the same genus.
>> >>
>> >>
>> >>"Zebitty" <zebitty at australis.aunz.com> wrote in message
>> >>news:91m7hc$e88$1 at gnamma.connect.com.au...
>> >>> Hi,
>> >>> I have recently started to learn a bit more about plants for my own
>> >>> purposes, and have noticed something that I haven't been able to
>> >>> answer.
>> >>Is
>> >>> plant taxonomy based purely on genetic relationships (much like
>> >>> animals)
>> >>or
>> >>> on something else. I ask because I notice several species of plants
>> >>> that look radically different in their adaptations to their
>> >>> environments and
>> >>yet
>> >>> have the same genus. Now generally animals of the same genus tend to
>> >>> look fairly similar. This does not seem to be the case with many
>> >>> plants. Why
>> >is
>> >>> this? Or is it just my lack of understanding of plant morphology?
>> >>>
>> >>> Thanks to anyone who helps
>> >>>
>> >>> Zebitty
>> >>>
>> >>> "If I have seen further, it is because I have stood on the shoulders
>> >>> of giants"
>> >>> Sir Isaac Newton
>> >>>
>> >>>
>> >>
>> >>
>> >
>> >
>> >
>>
>>
>> --
>> "Life wasn't meant to be easy....otherwise everbody would do it"
>> Rhys Parry
>
>







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