124 



THE SECOND BOOK OF BOTANY. 



other, each leaf of the upper pair being placed over 

 a space left by the lower pair. They are hence called 

 decussate leaves. In the same way the whorls of 

 leaves in verticillate-leaved stems are so placed that 

 they alternate with each other. 



Observe the arrangement of leaves in the stems 

 of grasses, and in stems with equitant leaves. 



Put by themselves all the stems in which the 

 leaves are neither decussate nor whorled. 



Examine them, one after the other, thus : Take a 

 small string, and, holding one end of it just below one 

 of the lower leaves of your specimen, carry it up and 

 around the stem (Fig. 270), so that it shall pass just 



FIG. 2TO. 



FIG. 271. 



under each successive leaf. Proceed in this way till 

 you reach a leaf standing directly over the one you 

 started with. Your string now includes what is 



