Hill: Penobscot Vegetation 397 



Association-types of the swamp series 

 Sedge stage. The continued growth of the sedges pre- 

 sent in the previous stage gradually results in the building 

 up of the substratum slightly above the level of the water 

 and affords a support for a large number of other grass- 

 like forms, characteristic among which may be mentioned: 

 Calamagrostis canadensis Scirpus atrocinctus 

 Poa triflora Carex strict a 



Glyceria canadensis Carex lurida 



Elcocharis tenuis Juncus effusus vars. 



Scirpus cyperinus Juncus canadensis 



Associated with these are numerous herbaceous species 

 which are equally characteristic of spring swamps and will 

 be considered under that heading. The sedge stage is very 

 apt to be telescoped by other stages and even obliterated 

 entirely. At best it is of short duration, shrubs invading it 

 almost from the start and soon replacing the grasses and 

 sedges as the dominant forms. 



Shrub stage. The most important shrub in these lake- 

 swamps is the alder (Alnus incana ) which is almost uni- 

 versally present. Other conspicuous species include: 

 Salix discolor Hex verticillata 



Myrica Gale Xemopanthus mucronata 



Spiraea latifolia Chamaeda phnc calyculata 



Pyrus melanocarpa Kalmia angustifolia 



Amelanchier laevis Rhododendron canadense 



Rosa nitida Vaccinia m corymbosum 



Rosa Virginia na Viburnum cassinoides 



Swamp forest stage. The end of succession in a well- 

 drained pond or swamp is a swamp forest which in most in- 

 stances represents a physiographic climax. The compo- 

 nent trees of this forest are usually the red maple, white 

 cedar and red spruce, and associated with them the ashes 

 (Fraxinus amcricana and F. nigra), larch (Laruv laricina) 

 and balsam fir in smaller numbers. These trees appear 



