THE WHITE LILY 153 



do not, however, form a complete ring. Now, this 

 arrangement in irregular concentric rings is character- 

 istic of the vascular bundles of most Monocotyledons 

 as distinguished from the Dicotyledons, in which we 

 usually find a single and regular ring. This difference 

 in the transverse section depends on the course of the 



-pc 



FIG. 57. Transverse section of the flowering stem of White 

 Lily. Somewhat diagrammatic, pc, thick-walled peri- 

 cycle, forming outer limit of central cylinder; 6 3 , one 

 of the small vascular bundles on its way from a leaf ; 6 2 > 

 bundle cut through on its inward course ; b lt one of the 

 principal bundles which form the inner ring. Magnified 

 about 20 times. (R. S.) 



vascular bundles through the stem. Here, just as in 

 Dicotyledons, all the bundles are common to leaf and 

 stem that is to say, each bundle in the stem is the 

 direct downward continuation of one which comes from 

 a leaf. The diagram (Fig. 58) will help us to under- 

 stand this, though it is much simpler than the reality. 



