abstracts: botany 133 



by a symbiotic fungus, of the sort known technically as an endotrophic 

 mycorhiza. There is strong evidence that this fungus acts as a purveyor 

 of nitrogen to the blueberry plant, a highly important function since 

 the formation of nitrates in these soils through the agency of nitrifying 

 bacteria is inhibited by the presence of organic acids. 



The experiments appear to warrant the following theory of the method 

 of nutrition of the swamp blueberry: (a) The swamp blueberry grows 

 in peaty soils which contain acid or other substances poisonous to many 

 plants, (b) As a protection against the absorption of amounts of these 

 poisons great enough to prove fatal, this plant, like many other bog and 

 acid-soil plants, is devoid of root hairs and consequently has a restricted 

 capacity for absorbing soil moisture. This low absorptive capacity 

 is correlated with a low rate of transpiration. Many bog shrubs, 

 altho living with an abundant supply of moisture at their roots, have 

 been recognized as showing adaptations for retarded transpiration simi- 

 lar to desert plants, (c) The special danger to which the swamp blue- 

 berry is exposed by reason of its low transpiration and its corresponding- 

 reduced capacity for absorption is insufficient nutrition. The danger 

 of nitrogen starvation is particularly great since these soils contain 

 very little nitrates, (d) Some bog plants similarly threatened with 

 insufficient nutrition, such as the sundews (Drosera), the bladderworts 

 (Utricularia), the pitcher plants (Sarracenia), and the Venus ffytrap 

 (Dionaea), possess means of securing the requisite nitrogen by catch- 

 ing insects and digesting and absorbing their nutritive parts, (e) In 

 the swamp blueberry the required nitrogen is secured in a different 

 way. The plant associates with itself a mycorhizal fungus which 

 is able to assimilate nitrogen from the surrounding organic matter, and 

 perhaps from the atmosphere also, and to convey it into the plant with- 

 out taking along with it a large amount of the poisonous soil moisture. 



Whether this theory of the nutrition of the swamp blueberry is or 

 is not substantiated in all its details by future investigation, it has 

 afforded a useful basis for cultural experimentation. A method of blue- 

 berry culture has been worked out under which these plants grow with 

 unexpected luxuriance and there is every prospect that the result will 

 be the establishment of a new agricultural industry, the commercial 

 cultivation of the blueberry. F. V. C. 



