Bogs, Their Nature and Origin. 



55 



which crowds out most other plants. However, its continuity 

 about the entire pond is broken by clumps of white birch (Betula 

 populifolia) (B), mountain holly (Nemopanthes fascicularis) (•), 

 larch (L. laricina) ( I ) and rhodora (Rhododendron canadense) 

 (jf) together with the high bush blueberry (Vacinium corym- 

 bosum) (o). On the south side of the lake, this shrubby vegeta- 

 tion comes down to the water's edge. Back of the leather-leaf 

 circumarea is one characterized by a sphagnum foundation, but 



Fig. 3. Distribution of plants in the flat bog known as Lost Pond, 

 Pocono Plateau, Pennsylvania. 



which is firm enough to permit the growth of such trees as red 

 maple (Acer rubrum), white birch (Betula populifolia) , black 

 spruce (Picea mariana), etc. The fourth, and last zonal arrange- 

 ment to attract our attention, is the one on the dry soil of the 

 morainic material, which completely surrounds the pond as a 

 series of low ridges curving about the shore. Here is found a 

 forest formation composed of white pine (Pinus strobus), black 

 spruce, white birch, red maple, trembling aspen (Populus tremu- 



