﻿THE GERMINATION OF HYDRASTIS CANADENSIS. 87 



who studied the germination of Eranihis hiemalis, Corydalis 

 cava, Ranunculus Ficaria, Bunium Bulhocastanum and Cycla- 

 men persicum. From his experiments it becomes apparent 

 that the medium is of but Uttle importance as long as proper 

 conditions of temperature and moisture obtain. The pro- 

 tective action of woods, preventing extremes of temperature 

 and moisture, has been shown by Ebermayer,* who is quoted 

 by Schmid in the paper just mentioned. Comparative ob- 

 servations made in Europe, in a beech-forest situated at an 

 altitude of 400 m., gave the following results: 



TABLE A. 





In the wood. 



In the open. 



Temperature 

 At surface 



One-half foot below surface 



max. 

 21.5° 

 18.4° 



min. 

 -2.5° 



max. 

 28.6° 

 24.5° 



min. 

 -4.6° 



SOIL AND SURFACE TEMPERATURES. 



From this it will be seen that at the surface the highest 

 temperature was 7.1° higher in the open than in the wood, 

 while I foot below the surface a difference of 6.1° C. was found. 

 It will also be noted that in winter the temperature of the soil 

 i foot below the surface was considerably higher in the wood 

 than in the open. 



Of paramount importance to the modified temperature of 

 the forest, is, as Schmid points out, the fairly uniform hu- 

 midity of its soil. In the woods there is but little danger of 

 desiccation as a result of prolonged summer-drought, which 

 in the open occasionally affects even the deeper layers of soil. 



In the wood, the natural habitat of Hydrastis canadensis, 

 where the ground is covered first by a layer of dry and decay- 

 ing leaves, and secondly by a layer of leaf-mold, the seed of 

 this plant evinces no trouble in penetrating to a depth of 

 several inches. To insure germination, similar conditions 

 would probably have to be reproduced. However, it remains 



* Ebermayer, E. Die physikalischen Einwirkungen des Waldes auf 

 Luft und Boden etc. 1, Aschaffenburg. 1873. 



