

480 BOTANICAL GAZETTE [june 



mosses. Competition 



summer is only a secondary 



consideration at all. If com 



• . • 



prime factor, we should find somewh 

 either in the horizontal series from 



from the standDoint of time from 



formed bv the vouneer stream 



ain of the mature 



mosses take an 1m 



This 



r 4ib 



has not been observed on any of the floodplains under consideration. 

 It is not, therefore, a case of being crowded out by other plants, 



inability to survive the unfavorable dynamic 



m 



elimi- 



mosses as was the active erosion of the earlier stages in 



stream's development. 



Spring stream succession. 



New 



numerous springs, the water of which is highly impreg- 



>ounds. As the water comes in contact with 



com 



the oxygen of the air, bog iron ore is produced which builds up 

 mounds about the outlets of the springs until the water can no 

 longer force its way to the top for escape, and finds a lower exit 



overcome. Very 



numerous species of plants make 

 structure of the tufa. Taking 

 coarse moss. Brachvthecium rivul 



. this tufa formation 

 'he chemical substanc 

 which, as they grow 



resist decay and form a porous rocklike mass. In the larger 

 stream forming the outlet of such springs at New Lenox are ^ 

 several species of Amblystegium growing on submerged sticks and 

 stones, but these do not enter into the tufa formation. A few 

 other species, not typically water forms, grow on sticks which 

 emerge from the water. 



A somewhat comparable case of the formation of travertine in 

 the waterfalls of the Arbuckle Mountains in Oklahoma has been 

 described by Emig (4), in which the two mosses Didymodon topha- 

 cens and Philanotis calcare are the species involved. Still another 

 species, Cratoneuron filicinum, has recently been collected by 



