sclerenchyma/prosenchyma

Doug Jensen dpjensen at berea.edu
Mon Apr 28 12:42:51 EST 1997


The problem I have with parenchyma, sclerenchyma, etc. is that people use them 
to refer to tissue types as well as cell types.  I try present plants as 
composed of 3 tissue types:  ground, epidermis, and vascular.  Then I can 
discuss the cells that make up each type of tissue.  I think this method is a 
bit less confusing to the students.

to Rod Savidge:  If you see Don Fowler around, tell him I said hi.  He's my 
uncle.

Doug Jensen
Berea College
_______________________________________________________________________________
Subject: sclerenchyma/prosenchyma
From:    savidge at unb.ca (Rod Savidge) at Berlink
Date:    4/28/97  12:52 PM

I have to disagree with the recent suggestion that "sclerenchyma should be
abolished".  In wood anatomy, `sclerenchyma' conveys the concept of
secondary-walled and lignified cells distinct from tracheary elements.
That is, sclerenchyma lack bordered pits whereas tracheary elements (at
least those of secondary xylem) exhibit bordered pits.  The distinction is
important, not only from the functional stand point of whether or not the
mature element is capable of water conduction, but also from the
developmental stand point of cellular differentiation and its regulation.

 `Prosenchyma' has largely disappeared from our terminology; however, for
early botanists prosenchyma comprised all woody elements (i.e., both
sclerenchyma and tracheary elements), whereas parenchyma comprised all soft
cells, whether present in xylem or elsewhere.  In my view, the use of these
two terms was, and still remains, a useful starting point in anatomical
classification.
 **********************************************************************
   Rod Savidge, PhD, Professor       |         E-mail: savidge at unb.ca
   Faculty of Forestry and          \|/
   Environmental Management      \   |   /     Phone:  (506) 453-4919
   University of New Brunswick   _\/ | \/_
   Fredericton, NB CANADA           \|/        Fax:    (506) 453-3538
   E3B 6C2                           |
 



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