84 PROCEEDINGS OF THE ACADEMY OF [March, 



OBSERVATIONS ON THE SOIL ACIDITY OF ERICACEAE AND ASSOCIATED 

 PLANTS IN THE MIDDLE ATLANTIC STATES. 



BY EDGAR T. WHERRY. 



In a recent paper^ the writer described the results obtained on a 

 trip in northern New England in June, 1919, where indicator solu- 

 tions were carried into the field and tests made of the soil reactions 

 of a number of species of Ericaceae and other families of plants 

 thought to be sensitive in this respect. ^ Both before and since 

 that trip similar observations have been made at a number of places 

 in Pennsylvania and adjoining states, and in the present paper some 

 of the results obtained are described^ The field work has been 

 carried out largely at the writer's own expense, in the course of vaca- 

 tion outings, but funds for certain trips were obtained from the 

 U. S. Bureau of Plant Industry, through Mr. Frederick V. Coville, 

 Botanist of the Bureau. 



The regions in which these observations have been made are 

 presented in the following table, with summaries of their dominant 

 geological and soil features. Those in the Appalachian Mountain 

 and Piedmont Provinces are given first, from northeast to south- 

 west, and then those on the Atlantic Coastal Plain, from north to 

 south. 



Table I. 



Features of regions studied. 



Locality State Surface Soil Dominant Ericaceae 



Geology Character soU reaction'' 



Appalachian Mountain and Piedmont. (Alleghanian Zone.) 



Swamps north Siliceoiis gla- Bog and up- Mediacid Abundant 



of Dover N.J. cial drift land peats 



^Rhodora, 21:33-49, 1920. 



^The use of indicators for this purpose has been described in Journ. Wash. 

 Acad. Sci., 10:217-233, 1920. Sets of indicators for field work are now on the 

 market. 



^Southern New Jersey will be discussed in these Proceedings at a later date. 



^The terms used for describing soil reactions have been defined in Journ. 

 Wash. Acad. Sci., 9:305, 1919. Specific acidity is the amount of acid, and spe- 

 cific alkalinity the amount of alkali, present in a given solution, with reference 

 to pure water as the unit. Specific acidity between 1 and 10 is called minim- 

 acid, between 10 and 100 subacid, between 100 and 1000 mediacid, and above 

 1000 superacid. Corresponding terms are used on the alkaline side. In addi- 

 tion, minimacid, neutral and minimalkaline reactions are grouped together as 

 circumneutral. 



