484 BOTANICAL GAZETTE [june 



sedges, all of the early aquatic plants having disappeared. Mosses 

 are about equally conspicuous over the whole of the sedge mat, 

 and consist chiefly of six species, all long-stemmed and of some- 

 what upright habit of growth. They form a rather close packing 

 about the roots of the other plants. All are very hygroscopic and 

 grow partly submerged. The most noticeable is Calliergon cordi- 

 folium. The others are Campylium stellatum, C. hispidulum, 

 Drepanocladus aduncus, D. fluitans, and Brachythecium rivulare. 



In the shrub association, where the shade is somewhat in- 

 creased, these species continue, but decrease in quantity. New 

 species do not seem to come in until the late shrub or early tree 

 associations which again show no distinct line of demarcation, 

 but merge into each other. It is here that we get the first develop- 

 ment of Sphagnum in the Mineral Springs bog. S. palustre occurs 

 usually in low wet depressions and has not formed a very extensive 

 growth either among the shrubs or in the tree association where 

 it becomes more abundant. 



Cooper (2), in his paper on the mosses of Isle Royale, discusses 

 the presence and absence of Sphagnum in bogs. He concludes that 

 Sphagnum comes in on the sedge mat following sedges of low growing 

 habits, which produce little shade and offer only slight obstruction to 

 the spread of the moss by vegetative growth. The inference is that 

 Sphagnum does not germinate in shade, although it may spread 

 into forests by vegetative growth from outside regions. 



This theory does not hold for the swamps and bogs of the 

 Chicago region. In the Mineral Springs bog the most common 

 sedges are relatively large and coarse. At Hillside the early sedge 

 stages are past, but the species still present are all tall and coarse. 

 In the former bog Sphagnum does not appear on the sedge mat; 

 in the latter S. recurvum has in most placed entirely replaced all 

 early associations. At Mineral Springs S. palustre begins in the 

 transition shrub-tree area, and becomes most abundant among 

 the tamaracks, where it is frequently found entirely disconnected 

 with any present Sphagnum region even in the transition associ- 

 ation. There is no evidence that it has spread from a less shaded 

 place of germination on the sedge mat, and there seems to be no 

 explanation of its presence other than that it has been able to 



