14 LABORATORY AND FIELD EXERCISES 



(2) Study the annual growth of the main central axis and 



of the larger lateral branches. How many seasons 

 of growth in length are represented in each ? 



(3) How many buds, including the subterminal and 



lateral buds, grew to produce the central axis and 

 lateral branches of the last season's growth at the 

 end of the shoot ? How many buds, including the 

 subterminal and lateral buds, grew into branches 

 in each of the previous seasons represented on 

 the shoot you are examining ? Is there a general 

 similarity in the number and size of the branches 

 produced each season ? Did the main axis of the 

 branch grow equally each season ? (See Fig. 6.) 



c. Vigorous buds and branches. Are the larger branches 



produced at about the same place, and are there 

 approximately the same number each season ? Is 

 there any similarity in the number and position of 

 weaker branches produced annually ? 

 (1) Study the buds laid down on the main axis and 

 the lateral branches for next season's growth. 

 Are some larger than others ? Have these larger 

 buds the same relative position as the stronger 

 branches on the annual growths of previous years ? 

 As the branch grows larger, what becomes of the 

 vigorous lateral branches and of the weaker ones 

 of each season? Observe a large branch to deter- 

 mine this point. 



d. Comparisons. Compare the elm branch and that of the 



spruce or pine already studied as regards the annual 

 growth of buds into branches. To what do the vigo- 

 rous seasonal branches of the elm correspond in 

 the pine ? Did you find anything in the pine or spruce 

 corresponding to the weaker annual branches in the 



