64 



OUTLINES OF PLANT LIFE. 



ducting of water, and bast strands for carrying foods. (See 

 ^^172-174, 197.) They are so placed that they alternate 

 with each other about the outer part of the stele (figs. 51, 

 53). The strands may be in contact with one another in 



Fig. 53. — Transverse section of the stele and a portion of the surrounding cortex of the 

 root of calamus s, s, innermost layer of cortex, adjoining outermost layer of stele ; 

 /, wood strands ; /A, bast strands. In the center of the stele and between the 

 bundles is conjunctive tissue. Highly magnified. — After Sachs 



the center, or the center of the stele may be occupied by 

 a pith (fig. 53). 



The number of vascular strands constituting the stele is 

 various, being as few as four or as many as forty. The 

 ordinary number, however, is from eight to twenty. (See 



fig- 53-) 



76. 3. The cortex generally consists of large thin-walled 

 cells which have become partially separated from one another, 

 leaving larger or smaller intercellular spaces (fig. 53). 



