sclerenchyma/prosenchyma

Rod Savidge savidge at unb.ca
Fri May 2 09:40:21 EST 1997


At 11:37 PM 4/29/97 -0700, Bob Vickery wrote:
>I assumed that 'sclerenchyma' is the name of a tissue and Rod assumed that
>it is the name of a cell type.  We were arguing at cross purposes. If
>botanists can't agree, what hope have the students got?

No, I was not assuming that sclerenchyma is the name of a cell type.  I
said that sclerenchyma conveys the concept of secondary-walled and
lignified cells lacking bordered pits.  For wood anatomists, sclerenchyma
comprises sclereids and fibres, and both subdivisions have been subdivided
further into quite a number of cell types.  To my knowledge, the term
`sclerenchyma' as originally conceived was never intended to be used to
designate either a tissue or any particular cell type, rather as a
convenient way of distinguishing one class of cells from another, i.e.,
secondary-walled and lignified cells which are not capable of conducting
water from another (viz., tracheary elements) which are.  (This is not to
say, however, that there are not some tissues, such as the woody coats of
many seeds, which are made up nearly entirely of sclerenchyma.  The seed
coat is the tissue, the various kinds of sclerenchyma constituents of the
tissue.)  

I think the same reasoning applies to parenchyma and prosenchyma.  It has
never been correct to consider any as either a tissue or a cell type.  If
folks are making that mistake today, should we argue that words that have
been used properly over two centuries should now be discarded because of
ignorant misuse, or should we argue that education in the areas of plant
anatomy and morphology is not being done adequately?

Rod 
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   Rod Savidge, PhD, Professor       |         E-mail: savidge at unb.ca
   Faculty of Forestry and          \|/
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   University of New Brunswick   _\/ | \/_
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