SOIL ACIDITY WHERRY. 



Table 6. — Soil reactions of rock ferns. 



259 



Name. 



Group 1. Sori marginal 



Cryptogramma Stelleri 



Pellaca glabella 



atropurpurea 



Cheilanthes lanosa 



tomentosa 



Group 2. Sori elongate. 



Asplenium Ruta-muraria 



resiliens 



viride 



Phyllitis Scolopendrium 



Camptosorus rhizophyllus 



Asplenium Trichomanes 



ebenoides 



platyneuron 



Bradleyi 



montanum 



pinnat ifidum 



gravesii 



Group 3. Sori various. 



Woodsia glabella 



alpina 



Ilvensis 



Dryopteris fragrans 



Woodsia obtusa 



Cystopteris bulbifera 



fragilis 



Polypodium vulgare 



polypodioides 



No. of 

 tests. 



15 



5 



30 

 15 



(2) 



15 

 15 



(2) 

 (2) 

 50 

 30 

 15(1) 

 50 

 5(3) 

 20 

 20 

 10 



15 



5 



25 



(2) 

 30 

 30 



30 

 50 



15 



Soil reactions. 



300 + 100 30+ 10 3 + 1 3 + 10 30 



(x) 



X 

 X 



(X) 



-t 



X 



Note to Table 6.— A Swedish ecologist, O. Arrhenius, has recently published the results of observa- 

 tions on the soil acidity of plant associations in the vicinity of Stockholm (Oecologische Studien in den 

 Stockholmer Schaeren. Stockholm, 1920. (In German).) Four of the above-listed species occurred there, 

 and his data, translated into terms of specific acidity, are as follows: 



Asplenium Ruta-muraria, spec. ac. 10 to 3+; Asplenium Trichomanes, spec. ac. 5; Woodsia Ilvensis, spec. 

 ac. 10 to 3+; and Polypodium vulgare, spec. ac. 13. The first of these results represents a slight extension 

 of range, but the others fall within the ranges here recorded. The essential agreement of measurements 

 made quite independently and in such widely separated regions furnishes a striking confirmation of the 

 deflniteness of the soil preferences of these species. 



The names used are those accepted by most present-day writers. 

 The number of tests made on each species is recorded, and, as about 

 three tests have customarily been made at each locality, the number 

 of localities represented is approximately one-third of the number 

 of tests. Tests made on soil adhering to the roots of herbarium 

 specimens, which seemed desirable in a few instances to supplement 

 field data, are distinguished by parentheses. 



The majority of the species tabulated clearly favor reactions lying 

 toward one side of the table or the other, and it is convenient to have 



