6o 



Richard H. Boerker 



so as to make it an ideal soil for germination. Hence we might 

 expect to find the longest germination periods in the sand. The 

 average figures show that this is the case in each group of species. 

 The shortest periods in every case are either in the loam or the 

 gravel because loam is unfavorable from one standpoint and 

 gravel from another. 



In comparing the check cultures of the three groups of species 

 it will be seen that xerophilous species germinate first, xero- 

 mesophilous next, and mesophilous last. In other words the 

 drier the habitat the sooner germination starts, granting that the 

 conditions are favorable. 



TABLE XII 

 The Effect of Light and Soil Texture on the Germination of Mesophi- 

 lous Species 



Species 



Pinus taeda 



Catalpa speciosa (Ind.). 



Quercus rubra 



Belula papyrifera 



Pinus lamberjiana . . . . 



Abies magnified 



Sequoia washingtoniana 

 Tsuga heterophylla .... 



Picea sitkensis 



Pseudolsuga taxifolia 

 (Wash.) 



Averages 2 



Light 



Check 

 Culture 



Medium 

 Shade 



Dense 

 Shade 



34 

 18 



40 



34 



70 36 



•c -. 



a. 1 — 



, I 



6 '34 



1 



28 '30 



32 



J16 

 26 



34 

 70 

 36 

 14 

 

 14 



22 54 14 



31.7 27.9:30.0 



Soil Texture 



Check 

 Culture 



Sand 



Gravel 



112 40 

 o o 



38 1 46 30 54 



1 34 

 16 80 



44 42 56 

 22 60 18 64 18 



I 

 18 

 50 48 

 22 1 

 8 

 64 



62 J22 28 38 ^44 36 48 



30.1,38.7 25.5140.4 27.9 40.7 27.0 



Tables similar to X, XI, and XII were constructed showing the 

 effect of these habitat factors upon the germination per cent, of 

 the species. This table is not given but the most significant facts 

 which it shows are given here and in a later table. It is interesting 

 to note that of the 37 species used in the experiments the highest 



2 Catalpa speciosa and Tsuga heterophylla not included in averages of 

 light cultures. Catalpa speciosa not included in soil-texture averages. 



