NO. I GROWTH LAYERS IN TREE BRANCHES — CLOCK ET AL. 225 



RELATIONS AMONG DIFFERENT SPECIES 



Differences and agreements among species are given in table 158 

 and are discussed on pages 220-221. Table 159 also shows how species 

 differ from each other during certain years. Little need be added. 



As table 158 shows, there are marked differences among species. 

 The extremes of zero and 100 percent agreement among branches 

 are not held exclusively by species represented by one tree only. 

 Otherwise, agreement varies from 6 to 82 percent for SA and TTL. 

 For species represented by more than two trees, agreements in percent 

 are: TTC, 58; TTP, 25; WCh, WPe, WPl, combined, 76; and 

 XSC, 75. The species designated TTP diverge from the other species 

 by the greatest amount. The three Washington tree species seem to 

 show the least divergence although they are from a decidedly dif- 

 ferent habitat. Lubbock trees hold a wealth of growth layers, many 

 sharply bordered, whereas the Washington trees are multiple by the 

 simple addition of a single highly diffuse intra-annual. This is not 

 universal by any means. 



EXTREMES OF MULTIPLICITY 



Table 159 (p. 222) gave an idea of the years with the greatest mul- 

 tiplicity. In descending order, they were 1940, 1936, 1935, 1944, 1939, 

 1938, and 1942. Photographs and drawings illustrate multiplicity 

 better perhaps than descriptions. Nevertheless, many examples have 

 been given in the chapter on classification. 



Here, section analyses will be summarized, included years given, 

 and number of tip flushes added where possible, in order to give an 

 idea not only of the extremes but also the range of multiplicity at the 

 extreme lower forest border. Those sections used have had their 

 growth layers dated exactly. Abbreviations are given on page loi. 



CCCb i-i-a (1937- 1941) 

 13 gis 4- 2 L -}- L's — 5 years. 



CM J i-i (1937-1940) 



a. 4 see -}- 3 gls -f- I psce + sL's + d ^L's — 4 years. 



b. 4 see -|- 4 gls -f- I psce -|- sL's -f- d iL's — 4 years. 



The 4 see in CMJ i-i do not necessarily mark the outer borders of 

 the years — i see marks 1938 and 3 see are included in 1939-1940. The 

 year 1937 has three less definite growth layers; they are designated 

 simply as "gls." In 1938 the psce was made by natural frost. 



