266 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1920. 



STUDIES ON ERICACEAE. 18 



Practically all of the members of the Ericaceae are acid-soil spe- 

 cies, so no comparison between their " class " and their geograhpic 

 range can be made. Nevertheless it is of interest to tabulate the re- 

 actions which they have been observed to favor and to bring out 

 the differences in the range of soil acidity shown by the various 

 species. 



Table 9. — Soil reactions of Ericaceae. 



Name (Gray nomenclature.). 



CLETHRA GROUP. 



Clethra alnifolia. 



PYROLA GROUP. 



Pyrola asarifolia 



elliptica 



chlorantha paucifolia.. 



Chimaphila maculata 



umbellata 



Moneses nniflora 



Pyrola rotundifoliaamerieana. 



secunda 



secunda obtusata 



chlorantha convoluta.. 



asarifolia incarnata 



MONOTROPA GROUP. 



Monotropa uniflora 



(Hypopitys) americana. 



lanuginosa . 



insignata... 

 Monotropsis odorata 



RHODODENDRON GROUP. 



Rhododendron maximum . . 

 (Azalea) nudiflora 



canescens 



arborescens 



calendulacea 



Kalmia latifolia 



( Rhodora) canadense 



Menziesia pilosa 



Kalmia angustifolia 



pollfolia 



Ledum groenlandicum 



(Azalea) viscosa 



Rhododendron lapponicum. 



Loiseleuria procumbens 



Phyllodoce cocrulea 



Leiophyllum buxifohum . . . 



ANDROMEDA GROUP. 



Leucothoe racemosa . 



Lyonia ligustrina 



Epigaea repens 



Num- 

 ber of 

 tests. 



300+ 100 30+ 10 3+ 



50 



Specific acidities. 



00 



X 



(x) 



(x) 

 (x) 



X 



(?) 



1B The combined data from : Soil tests of Ericaceae and other reaction-sensitive families 

 in northern Vermont and New Hampshire, Rhodora, 22, 33—49, 1920 ; and Observations on 

 the soil acidity of Ericaceae and associated plants in the Middle Atlantic States, Proc. 

 Acad. Nat. Sci., Philadelphia, 1920, 84-111. In the present compilation a few additions 

 have been made, as the result of further tests, chiefly in the State of Virginia. The 

 names in parentheses are subgeneric in Gray's Manual. The acidities in parentheses 

 represent tests in nurseries or on herbarium specimens. 



