A delayed response on "POC observations so far"

[Vincent, Leszek]

Hi POC colleagues,

Here's some 'bedtime reading'.

Recently there was discussion about the representation of unisexual
florets in a taxon which bears both functionally male & female florets
in separate flowering structures e.g. adequate representation of monoecy
in taxa such as Zea mays. Furthermore concern was raised about querying
an ontology, involving a monoecious taxon, for the term gynoecium - that
such a search should be able to retrieve gynoecium-related info.
associated with the tassel as well as the ear as in Zea mays.

Pankaj & possibly some others may recall that some of us visited this
area sometime last year & the synthesis of that dialogue was recorded in
the current ontology for Zea mays (freely available from
plantontology.org). But to show you an example of the tentative solution
to the challenge I've reproduced a portion of the representation below:

organ
  %tassel (functionally male inflorescence)
    <pedicellate spikelet of tassel
      <lower floret of pedicellate spikelet of tassel
        <gynoecial tissue (abortive) of lower floret of pedicellate
spikelet of tassel
        <lodicules of lower floret of ....
        <palea of lower floret of .....
        <stamens of lower floret of ....
      <lower glume of pedicellate spikelet of tassel
      <upper glume of .....
    <sessile spikelet of tassel
      etc.
  %lateral branch
    <ear (functionally female inflorescence)
      <pedicellate spikelet of ear
etc....

Yes, it is a little complex (view it via DAG-Edit for a clearer
representation than that provided here) but it is my/our best attempt
yet at capturing the biological complexity such that the true path rule
is met for this biological reality in Zea mays. Furthermore, it should
satisfy the query needs referred to above. Of course there may be other
considerations that have since transpired...

For me, as a botanist & plant systematist, I think it is a good solution
because it captures the ontogenetic detail for these structures and it
is also consistent with phylogenetic argument concerning these
structures - and consequently should be applicable to taxa, other than
Zea, where monoecy & dioecy is found.

It is true that some folk may not (at first) appreciate the biological
relevance of including both the androecium & gynoecium in both the
tassel & ear. My attempt to cover that 'base' is provided in the
definition for "floret". In this definition I spell out the ontogenetic
reality of both the androecium & gynoecium being initially present in
both the tassel & ear florets - hence their need to be included in both
the tassel & lateral branch/ear nodes. It also draws attention to the
putative phylogenetic necessity for such a representation. Implicitly
what I'm practicing is that ontogenetic & phylogenetic information are
both extremely important for inclusion in the application of the 'true
path rule'.

Here's the definition for floret (yes, it is detailed): 
"The floret is the individual flower of the Zea mays plant. In the grass
family (Poaceae, alt. Gramineae) each floret is typically bisexual
(perfect), possessing both an androecium and a gynoecium. Each floret
typically has a pair of bracts, the lemma and palea, which subtend the
floret. It is important to note that In Zea mays the florets of the
'tassel' are functionally male (the female component (gynoecium) having
aborted early on in development). The florets of the 'ear' are
functionally female (the male components (androecium) having aborted
early on in development). The possession of functionally male and
functionally female florets (or flowers) on the same plant is a
condition called monoecy. While Zea mays is functionally monoecious, the
presence of both androecial and gynoecial tissue in the early stages of
floret ontogeny is phylogenetically significant. Consequently, the
androecium is represented in the florets of the ear and the gynoecium is
represented in the florets of the tassel, even though either of these
whorls is absent in the functional florets. The inclusion of both whorls
in the floret ontology for the florets of ears and spikelets is based on
this phylogenetically significant ontogeny. East and Hayes (1911, p.
134-135) provided the following: "Perhaps it should be mentioned in
passing that the immature sex organs, so called, of maize seem endowed
with the power of becoming either stamens or carpels. One often finds a
normal ear ending in stamens, and nearly every plant produces lateral
branches which have carpels and stamens mixed together
indiscriminantly." Studies of mutants have explored these occurrences
and similar occurrences in tassels, corroborating the inherent bisexual
nature of the floret meristem prior to the subsequent development of the
monoecious condition." (the length of this defn. possibly provides
argument for the inclusion of some sort of comment field closely
associated with the definition?).

I've also been using the Derived/Develops_from relationship in the Zea
ontology. This relationship accommodates the temporal & spatial needs
associated with ontogeny e.g. the development of primordia.

You'll note, when browsing the ontology via DAG-Edit, that I still need
to provide definitions for some terms - an ever pressing need.

Let me have your candid comments/thoughts.

Leszek
 
===========================
P. Leszek D. Vincent Ph.D., FLS
Plant Science Unit, Dept. of Agronomy, 209 Curtis Hall,
University of Missouri-Columbia, Columbia, MO 65211-7020, USA.
Ph: (573) 884-3716 (Agronomy); Fax:(573) 884-7850;
Ph/Fax (Home): (573) 441-1228; 
Email: Leszek at missouri.edu
Yahoo! Messenger: leszekvincent
Plant Systematist on the Plant Ontology Consortium
Associate Curator, Dunn-Palmer Herbarium (UMO)
Research Associate, Missouri Botanical Garden, USA
CEO - PhytoSynergy, LLC
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