fio, 



TORREYA 



Vol. 34 September-October, 1934 No. 5 



Taxodium distichum in the Paleozoic area of Alabama 

 Roland M. Harper 



Of the two species of Taxodium in the eastern United States, 

 the smaller one, T. ascendens (or imbricarium) , the pond cypress, 

 seems to be strictly confined to the coastal plain, from Dismal 

 Swamp to eastern Louisiana. The other, T. distichum, which is 

 better known, and sometimes distinguished as the river cypress, 

 has a much wider range, and extends a little outside of the 

 coastal plain in a few places, notably along the Tallapoosa, Coosa 

 and Tennessee Rivers in Alabama and the Wabash in Indiana, 1 

 besides a few west of the Mississippi River which need not be 

 specially considered here. 2 



Its inland or northern limit may be determined partly by 

 some climatic factor, such as the average or minimum temper- 

 ature or length of growing season; but one should be cautious 

 in making such an assumption, for both species of Taxodium, 

 as well as many other trees, are successfully cultivated con- 

 siderably farther north than they grow naturally, apparently 

 indicating that when a tree is protected from competition it 

 can stand more extreme conditions of climate (and soil) than 

 it does in its natural associations. 



More likely the partiality of Taxodium distichum to the 

 coastal plain is connected with the fact that alluvial swamps 

 are much more common there, in comparatively level areas of 

 unconsolidated strata, than in the hill country, with relatively 

 hard rocks of Paleozoic age and older. It is an old species, ge- 

 ologically speaking, and its present colonies outside of the 

 coastal plain may have had their start many thousand years 



1 See C. C. Deam, Trees of Indiana, ed. 2, p. 30. 1921. 



2 For notes on the distinguishing characteristics of these trees and their 

 distribution see Bull. Torrey Club 29: 383-399. 1902; 32: 105-115. 1905; Pop. 

 Sci. Monthly 85: 351-352, 356-357. 1916; Geol. Surv. Ala., Monog. 9: 61-67. 

 1928. 



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