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Assertions re plant "cellularity"

Una Smith una at phy.duke.edu
Mon Jul 6 13:02:02 EST 1992


I read an interesting paper today.  The authors wrote:
"The assertions made in this paper are summarized in Table 1."
Here it is:

Table 1.  Philosophical assertions concerning plant "cellularity."
Assertions f-i provide the principal foci for biomechanical analysis
of plants.

a.	The concepts of the organism and the cell are logically
	independent of one another.
b.	Multicellularity is not a requisite condition for the
	expression of morphological complexity.
c.	Multicellularity is the result of a highly specialized
	developmental scheme in which cytokinesis and nuclear
	divisions are precisely correlated.
d.	The protoplasm is the fundamental organismic unit.
e.	In multicellular plants, the protoplasm is incompletely
	partitioned by an apoplastic (cell wall) infrastructure.
f.	In addition to providing an opportunity for the physiologic
	and reproductive specialization of the protoplasm, the
	apoplastic infrastructure provides mechanical support.
g.	The apoplast is a shared-primitive condition in all plants,
	i.e., unicellular, colonial and multicellular organisms
	have an apoplastic-symplastic structure.
h.	The "internalization" of the apoplast has occurred in at
	least two different ways (siphonous and multicellular plants).
i.	Only one of these (multicellularity) permits the acquisition
	of large size in a terrestrial habitat.
j.	Multicellularity was an exaptation for the colonization of
	land by plants.


And here's the reference, set in BIBTeX format:

@inbook{NiklasKaplan1991,
	author = {Karl J. Niklas and Donald R. Kaplan},
	year = 1991,
	title = {Biomechanics and the Adaptive Significance
		of Multicellularity in Plants},
	booktitle = {The Unity of Evolutionary Biology:
		Proceedings of the Fourth International
		Congress of Systematic and Evolutionary Biology},
	volume = 1,
	editor = {Elizabeth C. Dudley},
	publisher = {Dioscorides Press},
	pages = {489--502}} 

I am curious as to why the authors use the term "protoplasm"
to refer, apparently, to the entire (multicellular) organism,
rather than "individual".  I am confused about what the term
"individual" means when applied to plants.  Any comments?

What are the fundamental characters common to all things we
categorize as plants, whether unicellular or multicellular?
-- 

Una Smith   una at phy.duke.edu    School of the Environment
                                Duke University
                                Durham, NC  27706



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