168 



(loquat) was badly nipped, and lost some of its branches, but 

 bloomed again the following winter as usual. (It never makes any 

 fruit here, as it does in Florida.) But curiously enough, Elaeagnus 

 pungens, which Penfound and Mackaness reported as injured by 

 the 20° temperature in New Orleans, did not seem to suffer notice- 

 ably from the zero weather in Tuscaloosa. 



The frost of April 12-13, with a minimum recorded tempera- 

 ture of 26° at Tuscaloosa, came when the leaves of most of our 

 deciduous trees were about half grown, and some of them were in 

 bloom. The following morning I went about ten miles up the 

 Warrior River, and found the leaves of all species of Hicoria, 

 Onercus and Fraxinus frozen and wilted ; even Quercus montana, 

 which grows as far north a's Massachusetts. The same thing hap- 

 pened to the leaves of Magnolia macrophylla on the campus, and 

 doubtless in the woods too. But herbaceous plants seemed to be 

 almost uninjured, except for a few with very delicate foliage, such 

 as Osmorrhisa (W ashing t onia) . 



Other effects of this same killing frost became apparent later 

 in the year. It destroyed the fruit crop on all or nearly all the 

 Hicoria, annual- fruited Quercus, Vitis, Diospyros, and cultivated 

 pecans and peaches in the northern half of Alabama. But in Autauga 

 County, near the center of the state, which I visited in late summer, 

 the pecans, muscadines and persimmons seem to have borne a 

 normal crop, or nearly so. 



Some other effects of the cold winter did not become evident 

 until fall. It seems that the falling of deciduous leaves is due not 

 only to decreasing temperatures in the fall, but also to the accumula- 

 tion of mineral salts in them, which the tree gets rid of and returns 

 to the soil in that way." It is doubtless largely for this reason that 

 evergreens are characteristic of poor soils and cold and dry climates ; 

 and on very poor soils the leaves of trees may last two or more years 

 before they get so impregnated with mineral matter that their 

 usefulness is ended. 



The trees around Tuscaloosa got such a late start in 1940 that 

 by the second week in November most of the deciduous leaves had 

 not yet matured sufficiently to form the abscission layer at the base 

 of the petiole, which detaches them from the stem. So a severe 



2 See Am. Fern Journal, 9: 100. 1920. 



