398 Proceedings Portland Society Natural History 



first as scattered individuals in the shrub stage, but even- 

 tually come to cover the whole area. During this process 

 the shrubs are not killed out but remain to form a part of 

 the abundant undergrowth characteristic of such woods. 

 Various herbaceous species, common in the two preceding 

 stages, also occur and with them such other forms as : 

 A thy Hum Filix-femina Carex scabrata 



Osmunda regalis Arisaema triphyllum 



Taxus canadensis Habenaria fimbriate/, 



Glyceria nervata Thalictrum polygamum 



Bromus cilia tus Ha ma metis virginiana 



Carex Goodenowii Scutellaria lateriflora 



Carex leptoncrvia Viburnum dentatum 



Carex intumescens var. Solidago canadensis 



Fernaldii 

 In situations where, for some reason, the substratum is 

 less wet than ordinarily the trees of the swamp forest may 

 be replaced by others. The spruce and fir may increase in 

 abundance until they become dominant ; and in very favor- 

 able places deciduous trees of the regional climax may come 

 in. The typical climax forest is, however, never attained 

 in such places. A wooded swamp along the outlet of 

 Craigs Pond in Orland is illustrative of this mixture of 

 lowland and upland types, comprising the following species : 

 hemlock, white cedar, red oak, beech, red maple, moosewood, 

 and Fraxinus pennsylvanica, with an undergrowth of moun- 

 tain maple, Hamamelis virginiana and Viburnum alnifolium. 

 The normal succession in well-drained ponds and swamps 

 outlined above may be taken as representative for the en- 

 tire region, although the several stages may not always be 

 developed. Telescoping of the various zones is extremely 

 frequent and often one or more stages may be entirely 

 omitted. In many lakes, as shown in Figure 31, there is 

 only a narrow border of shrubs between the water and the 

 forest. 



Tn a few instances all the stages are present in their most 



