PLANT TISSUES 



105 



gated and more or less obtusely or taper ended, its component ele- 

 ments are termed Scierenchyma fibers. These fibers are frequently 

 spindle-shaped, contain air and exhibit oblique slits in their walls. 

 They are either polygonal, rectangular or somewhat rounded in 



FIG. 43. Scierenchyma fibers from different sources. I, From powdered 

 cinnamon bark; 2, End of bast fiber of flax stem showing transverse markings 

 (6); 3, middle portion of flax fiber showing characteristic cross markings at 6; 4, 

 bast fiber from cinchona bark; 5, branched bast fiber from choke cherry bark; 

 6, above, end, and below, median portion of bast fiber of jute. All highly mag- 

 nified. 



transverse section. They occur in various parts of roots, stems, 

 leaves, fruits and seeds as supporting elements. When Scierenchyma 

 fibers occur in the xylem region of fibro-vascular bundles they are 

 termed Wood Fibers; when they appear in the ph"o2m region, 

 Bast Fibers. 



