xylem

David Haas dhaas at CHI1.UNCFSU.EDU
Thu Mar 14 15:15:18 EST 1996


Jim Perry said:>> 
> 
> At the risk of sending something that most of us might know...


There's no risk here.   I 've always thought that fibers were more 
specialized and evolved from tracheids.   Also I thought that the 
first vascular plants had tracheids not fibers.  Please set me 
straight.  What about Rhinia and Cooksonia sp.  are there now fossils 
that  pre date these early plants.    I took Paleo-bot  in the 
Paleozoic ! 

> The evolution of xylem tracheids is presumed to have occurred as a result of 
> modification of fibers, and subsequent to that, vessel members to have evolved 
> from tracheids. Inasmuch as early land plants were likely thallose, and were 
> in fact probably more accurately described as amphibious, any development of 











********************************************
Dave Haas                               
Department of Natural Sciences    
Fayetteville State University    
Fayetteville, NC 28303           
********************************************

"More than any other time in history, mankind faces a crossroads. One 
path leads to despair and utter hopelessness.  The other, to total 
extinction.  Let us pray we have the wisdom to choose correctly." - 
Allen Konigsberg.



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