Please enlighten my ignorance 8-)

Cereoid CEREOID at prodigy.net
Wed Jan 10 08:22:14 EST 2001


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?
>
> 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.
>
> 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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