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frost the night of the 15th- 16th caught many of them still green, and 

 caused them to wilt and hang down much as a late spring frost 

 would. And there they hung until about a week later, when a rain 

 added enough weight to bring most of them down. 



This was especially noticeable in Ginkgo, Celtis, Broiissonetia, 

 PlatauHS, Magnolia niacrophylla, Liqitidauibar, Albiczia, Acer sac- 

 charinuin, Hibiscus Syriacus, Mclia and Lagcrsiroeuiia, all culti- 

 vated in Tuscaloosa, some native and some exotic. I did not have 

 a good opportunity to go out in the woods at that time to see how 

 the wild trees were affected. 



In this connection it seems worth while to digress and note 

 another instance of the duration of leaves being determined by 

 age, in which temperature did not seem to be a factor. On and 

 near the University campus there are a few young specimens of 

 Quercus lobata, the California white oak, from seeds I planted 

 in the winters of 1936-37 and 1937-38. The largest of these in the 

 middle of 1940 was about five feet tall. In its native haunts in Cali- 

 fornia it gets no rain in summer, and presumably makes very little 

 growth at that season. But July, 1940, was unusually rainy in 

 Tuscaloosa, with 12.55 inches of rain instead of the normal of 5.21, 

 and the little tree added about a foot to its height during that 

 month. 



In November it dropped its leaves, like other deciduous trees, 

 except on the uppermost foot, where the leaves had not yet served 

 their time, so to speak. A photograph of it taken on December 18 

 showed the young terminal shoot still leafy and the rest of the 

 tree bare. After that these last and youngest leaves dropped 

 gradually, but the uppermost and youngest one hung on until 

 about February 1, when it was about six months old, which is the 

 approximate normal duration of deciduous leaves in this climate. 



University, Ala. 



