1920] TAYLOR— SUCCESSION OF MOSSES 467 



rostratus, and Mnium cuspidalum; while the lower third of the 

 slope is nearly covered by one hypnaceous species, Plagiothecium 

 deplanatum. The entire surface is well supplied with herbaceous 

 undergrowth, but this has not yet been able to supersede the 

 mosses, which, because of absence of decaying woody material, 

 are found almost entirely on the ground. As the ravine widens 

 and enters upon its second period of denudation, more light enters, 

 and the mosses are gradually eliminated by their being a favorable 

 habitat for the germination of seedlings of higher plants which can 

 endure a greater degree of evaporation. 



The oak uplands adjoining these ravines are characterized by 

 an extremely impoverished moss flora with the exception of Catha- 

 rinea undulata, which may occur frequently. This is almost 

 equally true of the oak-hickory morainal forests at Joliet, New 

 Lenox, and Palos Park. Catharinea undulata is present in all, 

 Physcomitrium turbinalum occurs along paths, and at Palos Park 

 Leucobryum glaucum is an occasional species. At Wheeling, 

 Illinois, just west of Glencoe on the Des Plaines River, are upland 

 morainal forests which are much more mesophytic than those 

 just mentioned. Of these we may make two general divisions: 

 those which have been pastured so that there are few shrubs and 

 the herbaceous growth is almost confined to grasses, and those 

 which have a mesophytic undergrowth both shrubby and her- 

 baceous. In the unpastured woods, as a marked contrast with the 

 other oak woods just mentioned, mesophytic mosses are common 

 both on logs and on the ground. Among these are Thuidium 

 delicatulum, Mnium cuspidalum, Catharinea undulata, and Clima- 

 cium americanum. In the more open woods which have been 

 partly cut over and subject to grazing, these same species continue 

 on as relics, but are less abundant than before. With these may 

 be Leucobryum glaucum, Dicranum scoparium, Polytrichum com- 

 mune, and Ceratodon purpureus. It is not unusual to see rather 

 large areas given over to Leucobryum and Dicranum alone or mixed 

 with Polytrichum, Catharinea, and Thuidium. Close to the river, 

 however, along the well drained bluff, we once more find only 

 Catharinea on mounds and Physcomitrium with sometimes Funaria 

 hygrometrica along paths and in tracks. 



