290 



Proceedings Port. Soc. Nat. Hist. 



FiGTRK 5. — Distribution of Viburnum dentatum, a representative 

 AUeghanian species. 



leaf mould beneath these trees occur Adiantum pedatum, 

 Actaeci rubra, Carex novae-angliae, and other species found 

 nowhere else in the region. The reason for the restriction 

 of the species to these areas is readily apparent. They are 

 plants which require a good percentage of basic material and 

 they are unable to obtain the necessary food in the acid or 

 neutral silicious soils which prevail elsewhere. As will be 

 shown later, these plants should be considered as relic rather 

 than pioneer types, and they persist here only because of the 

 extremely favorable environmental conditions. Other Al- 

 leghanian species are more tolerant than these rich woods 



