268 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1920. 



peculiarities of the flora of the Pine-Barren area. The presence of 

 plants, often found in peat bogs, around the borders of salt marshes 

 can likewise be explained on the basis of soil acidity. 20 



The application of these methods to the study of the soil for the 

 cultivation of native plants has only just begun, but it has proved 

 easy to grow a number of species ordinarily regarded as impossible 

 to cultivate by seeing to it that the soil possessed a reaction approach- 

 ing that which had been found to be optimum for the plants in 

 nature (as shown in the tables above). By way of illustration of 

 what can be done along this line, two photographs of Shortia galaci- 

 folia in the writer's garden are here reproduced on plate 2. The 

 upper picture shows how this plant behaved the first year after re- 

 ceipt from a nursery, in which it had been grown in soil of a low 

 degree of acidity (specific acidity 3). The plant was placed in soil 

 of specific acidity 100, and the lower picture shows what happened 

 the next year. Its optimum acidity is evidently nearer the second 

 than the first specific acidity. 



20 Plant distribution around salt marshes in relation to soil acidity, Ecology, 1, 42, 1920. 





