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 ? 
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Fic. 90. Development of bark on cottonwood branches 
4, young twig showing terminal bud ¢.b, leaf buds /.b, and leaf sears /.s, the bark 
being almost smooth except where lenticels appear; B, an older branch in longi- 
tudinal and transverse view, showing the bark ¢ as it begins to be broken and 
ridged, and the leaf scar 7.s; (, still older branch, showing the bark after it has 
become decidedly ridged, and also a branch scar 0.s. 
