1920] 



TAYLOR— SUCCESSION OF MOSSES 



459 



ravines, however, on slopes with a northern exposure or otherwise 

 protected from desiccation, certain species may be fairly frequent. 

 Thelia Lescurii, a gray-green moss growing in loose mats, is 

 dominant and sometimes covers areas of several square feet. 

 Anomodon rostratus also appears frequently, and A. attenuatus 

 occasionally. Climacium americanum and Rlwdobryum roseum 

 may be found in sheltered spots but not in large quantities. 

 Ceratodon purpureas is characteristic in open, less shaded places, 

 while Catharinea undulata occurs here and there. A thick con- 

 tinuous moss carpet is never found among the oaks as in the pine 



TABLE I 

 Presence of moss species in associations of sand dune succession 



dune. As we go still farther south into the later stages of the 

 oak associations, the moss flora becomes less, until about the only 

 species left are Thelia Lescurii and Catharinea undulata in shaded 

 places, with Ceratodon purpureus and rarely Bryum argenteum 

 where the sand is more exposed. In forests where white oak is 

 dominant and the forest floor is free from fallen trees, as is the 

 case in many oak forests in this region, Catharinea undulata is 

 usually the only moss species to survive. Table I shows the suc- 

 cession of mosses as they have been found in the xerarch series of 

 the sand dunes. P indicates presence of species. Only the 

 species which occur in two or more associations are included. 



