.*}12 Proceedings Portland Society Natural History 



M. Stetson, who rendered invaluable aid in the securing of 

 bhe photographs. 



Nomenclature and Ecological Classification 



In the present work the nomenclature of the ferns and 

 spermatophytes will follow that of the author's paper on 

 the Vascular Flora of the eastern Penobscot Bay region 

 (15) ; while that of the bryophytes will follow Evans and 

 Nichols's Bryophytes of Connecticut (6). The nomencla- 

 ture of the lichens is that of Mr. George K. Merrill, who has 

 very kindly checked over all references. 



The system of ecological classification to be used follows 

 that outlined by Nichols (22). Briefly this system may be 

 summarized as follows : 



The fundamental unit of vegetation is the association, — 

 a plant community characterized by its essentially homo- 

 geneous physiognomy and ecological structure, and florist ic 

 composition at least as regards the dominant species. The 

 vegetation of any given region comprises a complex of such 

 associations. The individual associations may be classified 

 according to their physiognomy and ecological structure, 

 their geographic, and their successional relations. 



Considered as to their physiognomy and ecological struc- 

 ture all associations which resemble one another in these 

 respects may be referred to a common association-type. 

 From the standpoint of the geographical relations two other 

 vegetation units may be recognized: the climatic forma- 

 tion which comprises a complex of associations occupying 

 an area with uniform climate ; and the physiographic for- 

 mation which consists of a complex of associations which 

 occur in areas which represent units in their relation to the 

 larger physiographic features of the region. 



In discussing the vegetation of the Penobscot Bay region, 

 the climatic and physiographic formations will be outlined 

 first and then the association-types. Under the latter the 



