110 Harper: Observations on Taxodium 



An 



hnbri- 



cariinn which had been felled, showed the structure of the base of 

 the trunk in cross-section. The broad longitudinal ridges of wood 

 become pressed against each other as they grow, closing the 

 sinuses between them (as shown in the accompanying diagrams), 

 while in T. distidmm the sinuses are open and rounded and the 

 ridges rather sharp. Ericaceous shrubs (such as Pieris nitida and 

 Leucothoe racemosd), growing close to the base of such a tree, 

 often have their stems caught in the embrace of the swelling 

 ridges and then appear as if growing out of the Taxodium above 



the ground. The 



phillyrcacfolia * may 



have originated in some such way. In both species the base 

 seems to be always hollow in old specimens, and knees often 

 grow inside it. > 



Figure 5. Ideal cross-sections of hollow enlarged base of trunk oiTaxodium ivihri- 

 carium (<z) and T. dhfichuin [b). (The annual rings in reality would be ten to filty 

 times as numerous as they are shown here. ) 



Another distinction (though rather a subtle one) between these 

 two species is that in T. disticJiitm the trunk is straight but not 

 always erect, while in T. imbricm'hnn it is erect but not always 

 straight 



The following additional notes on the distribution of the two 



M 



L 



southeastern species may be of interest. 



Taxodium distichum 



In Georgia the inland limit of this species reaches the fall-line 

 at the eastern border of the state, but diverges widely from it west- 

 ward, following approximately the outcrop of the Eocene forma- 



*See Torreya 3 : 21, 22, February, 1903. 



