BUDS AND BRANCHES 



105 



the leaf into the stem. In dicotyledons there are usually 

 about as many such dots on the scar as there were principal 

 veins in the leaf or leaflets of a compound leaf. Why? 



-b.8 



FIG. 90. Development of bark on cottonwood branches 



A, young twig showing terminal hud t.b, leaf buds Lb, and leaf scars sc, the hark 

 being almost smooth except where lenticels appear ; B, an older branch in longi- 

 tudinal and transverse view, showing the bark c as it begins to be broken and 

 ridged, and the leaf scar sc; C, still older branch, showing the bark after it has 

 become decidedly ridged, and also a branch scar b.s. 



