﻿ig 1 6] PFEIFFER-OPHIOGLOSSUM VULGATUM 510 



prairie plants. Spots have been burned, and here the plants show- 

 very distinctly, owing to a partial elimination of the grasses and 

 other plants which ordinarily 

 tend to obscure the smaller 

 Ophioglossum plants. Where 

 there is much shade. Sdagi- 

 nella apus and Aneura pin- 

 guis occur, as in the Thismia 

 patch, which is close at hand. 

 The habitat is evidently low 

 and wet, inundated in spring. 

 Early in July, Riccia fluitans 

 in small amounts was also 

 found, and late in July 191 5. 

 after a rather wet month, 

 some of the field was under 

 water. There were, however, 

 hummocks as well as more 

 extensive little plots not sub- 

 merged. Compared with the 

 other situation in the Chicago 

 region where O. vulgatum has 

 been found, that is, near 

 Gary, the present station in 

 the southeast outskirts of 

 Chicago seems wetter. The 

 difference noted in the time of 

 maturity of. fertile spikes in 

 the two areas is probably 

 related to the difference in 

 situation. In the moister 

 place, some spikes were still 

 unshed on July 24, whereas 

 the spikes were already gone 

 in the drier, less protected 

 Gary situation, on July 15. 

 that inundation favors spore germination, one may suppose that 



Working on Campbell's theory 



