NO. I GROWTH LAYERS IN TREE BRANCHES CLOCK ET AL. 



285 



Con T 2-1 i-a, from the second tip flush of 1941, actually contains 

 more growth layers than does 2-16-b. The plus sign with the number 

 of years refers to that portion of 1944 from the start of growth to 

 May 22, an interval during which an incomplete growth layer was 

 formed. The localized occurrence of certain growth layers exists in 

 the trunk and thus resembles the same feature in branches. 



/= 



/• 



/ I'c" 



/ / 



/ / 



// 



/M}. \ 



I 



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\ '943 , 



2-7 

 2-4 



2-6 

 2-5 



\ \ 

 \ \ 

 \ \ 



:\ \ \ 



/ / / b 4?^\2-l3 \ \ 



/ / / \ \ \ 



0,4,8 ,'j g-rJ6_^ ^ ^ 



y ' Kf>^ ^^ ?i? i t i t 



3 V3 p\^ 



1940 , \ JML l'^i-'^l> 

 V III 



Fig. 51. — Leader of Pinus taeda (Con T 2-14 to 2-16, and 2-1 1) with branch, 

 Con T 2-8, to show annual increase in diameter flushes and tip flushes. Cross- 

 bars represent terminal bud scale scars. Capital letter refers to unstained block 

 removed from leader at early part of 1940 growth. Small letters refer to position 

 of stained sections. Figures opposite the letters give the number of growth layers 

 in the sections represented by the letters. Larger scale for branch 2-8 only. 



Much work remains to be done in the task of tracing growth layers 

 from the branches down the length of the trunk and in determining 

 their characteristics. However, all the information so far available 

 indicates that there is no difference between branches and trunk. It 

 is possible that the trunk may have slightly less multiplicity and more 

 subdued localization of growth layers than the branches, but at present 

 such is not borne out by our observations. 



