The Soil Reactions of the Ferns of Woods and 
Swamps. 
EDGAR T. WHERRY 
The ferns to which this essay is devoted are on the 
whole less sensitive to soil acidity and alkalinity than 
‘ those which grow on rocks, to which attention was 
directed in a previous paper.! It seems worth while, 
however, to place on record what data have been ob- 
tained on testing the soils surrounding their roots by 
the indicator method. The introductory and explana- 
tory portions of the paper cited apply sufficiently well 
to the present one to make their repetition unnecessary. 
The data are presented in similar form, although a 
slightly different method of classification seems desir- 
able, for additional types of reaction-range are repres- 
ented. The following designations are used in the class 
column of table 1: 
AA, intensely acid; appearing to thrive only in medi- 
acid soils. 
A, acid; growing well in soils of practically all degrees 
of acidity. 
I, indifferent (relatively); appearing to thrive in both 
acid and alkaline soils, so long as neither reaction is 
extreme. 
C, caleareous or circumneutral; growing best in neu- 
tral soils, though extending throughout what is termed 
the circumneutral range (specific acidity 10 to alk. 10). 
No instance has been found of a species which will not 
grow in neutral or slightly acid soils as well as in actually 
alkaline ones. 
In the last column the geographic range is described 
by S for southern, N for northern, and a dash,—,when the 
species is wide-ranging. 
tsAmer. Fern Journ., 10: 15-22, 45-52, 1920. 
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