486 BOTANICAL GAZETTE [june 



standing water. A large number of species of moss which have 

 not been found in the previous bog associations occur here, on the 

 ground, on sticks, or on logs. Calliergon cordifolium, the two 

 species of Campylium, the Brachythecium, and Drepanocladus 

 aduncus continue, often on partly submerged sticks. In slightly 

 higher situations, but on ground that is still very wet, are 

 Lencobrxum glaucum, Climacium americanum, and Thuidium 

 delkatnlum. With the exception of Leucobryum, these species 

 are also found on logs and sticks. Anomodon rostratus comes 

 in where there is less moisture, particularly about tree bases. 

 Here, as in the other mesophytic moss habitats, the soft hygro- 

 scopic mass of moss tissue forms a favorable place for the ger- 

 mination of tree seedlings and the seeds of other plants. As one 

 approaches the higher land adjoining the sand dune to the north, 

 the moss growth becomes less in quantity, but does not change 

 very much in species until the dune itself is reached. 



In the Hillside bog, a large part of which has reached the 

 shrub stage, but in which there is much less water than at Mineral 

 Springs, Sphagnum recurvum has been, and in places still is, the 

 dominant vegetation. It must have reached a very luxuriant 

 development in the recent past, but is now on the decline. In 

 many places Aulacomnium palustre forms a second moss stage 

 growing on Sphagnum, and this is frequently accompanied by 

 Polytrichum commune. Cooper describes such an association in 

 the Sphagnum bogs on Isle Roy ale. The bog itself has not yet 

 developed the tree association, although with respect to moisture 

 conditions it has advanced much beyond the bog at Mineral Springs. 

 It is surrounded by climax beech-maple forest, and it is quite likely 

 that this will be the fate of the bog if left to nature's influence. 

 In the adjoining beech-maple forest Catharinea undulata is again 

 the only moss of any prominence. 



Table II represents the hydrarch succession from open water 

 of lagoons and ponds to the climax forest. Once more the great 

 importance of pioneer mosses in the advancement of the higher 

 plant associations is shown. The economic value of shallow 

 ponds is slight; while on the other hand they may be very injurious 

 in that they harbor larvae of insects, harmful to man, so that the 



