1920] — Wherry,—Soil Tests of Ericaceae and Other Families 45 
A number of interesting relationships are brought out by Table III. 
First of all it is noteworthy that the plants studied fall into two main 
groups with respect to their optimum reactions, one in which the 
optimum value is specific acidity 30 or less, the other in which it is 
100 or greater. The former corresponds essentially to the Pyroloideae, 
the latter to the Kricoideae and Vaccinoideae, in the Gray classifi- 
cation. 
'The range of reaction shown by the members of the Pyroloideae 
is inclined to be rather wide, being from 300 to 3 in a few cases. That 
they are not by any means indifferent to soil reaction, however, is 
shown by the fact that the optimum lies in all but the last two 
cases within the narrow range of specific acidity 10 to 30. 
The last two Pyrolas show such a striking contrast in their soil 
acidity as to warrant special discussion of them. "Typical Pyrola 
asarifolia was found growing along Willoughby Lake, in rather dry 
soil containing calcareous rock fragments, and being throughout 
practically neutral in reaction. It is also present in certain woods 
near St. Johnsbury, in damp material of similar reaction. It is, 
indeed, often classed definitely as a calcicole.! On the other hand 
the variety incarnata is abundant in the Peacham swamp, west of 
St. Johnsbury, growing well up in the hummocks of sphagnum, 
where the specific acidity is 300; and it was also found in a similar 
situation in swamps south of Willoughby Lake. Additional observa- 
tions on both of these plants, and especially on the intermediate 
forms reported by Fernald,? would be desirable to ascertain whether 
there is any constant and definite correlation between soil acidity 
and plant characters. Cultivation of these plants in soils of different 
reactions should also be tried. — 
In the Ericoideae and the Vaccinoideae, at least in the series of 
species here studied, the range of reaction tends to be rather restricted, ` 
sometimes being only from 300 to 100, and the optimum reactions 
all lie within a narrow range. Several of the individual species, 
however, deserve brief comment. It is curious to note that while 
Rhododendron lapponicum is here found to ke a mediacid soil species, 
and has been recorded by Fernald? from several alpine granitic regions, 
in all of which the reactions are no doubt similar, in northern Sweden 
! €f. Blake, S. F. The Flora of New Brunswick. Ruopora, xx. 101 (1918). 
? Fernald, M. L. Pyrola asarifolia Michx. var. incarnata, n. comb. Ruopora, 
vi. 178 (1904). 
3 Rnopona, ix, 162 (1907). 
