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Editor, Alexander W. Evans, MD., Ph.D. 



Associate Editors, Jean Broadhurst, Ph.D., J. Arthur Harris, 

 Ph.D., Marshall Avery Howe, Ph.D., Michael Levine, Ph.D., 

 George E. Nichols, Ph.D., Arlow B. Stout, Ph.D.. Norman Taylor. 



Delegate to the Council of the New York Academy of Sciences, 

 John Hendley Barnhart, M.D. 



SOIL PREFERENCES OF SCROPHULARIACEAE 



By Francis W. Pennell 



Fifteen times during the course of my series of articles on the 

 " Scrophulariaceae of the Local Flora," which appeared in 

 ToRREYA during 1919, have I made the same mistake — an error 

 which to a person with a chemical knowledge of soils may appear 

 glaring. One correction will serve for all: for "potassic soil" 

 read "non-calcareous and non-magnesian soil." 



It is easy for those of us who are interested in plant-identity 

 and plant-distribution to realize that for each species there is a 

 soil of optimum chemical composition as well as one of optimum 

 physical composition. The writer's first original scientific 

 study was an analysis of the flora of the Serpentine Barrens of 

 extreme southeastern Pennsylvania, and there, on soil identical 

 in texture with that of other barren hills of the section, the 

 Serpentine would present invariably its definite alliance of inter- 

 growing species — certainly the obvious explanation was the 

 presence in the soil of magnesium as a preponderant element. 

 With nearly equal sharpness one may denote the species growing 

 upon soils with calcium as the main determining element. 

 Other soils may not so readily be disposed into like groups, yet 

 the remaining aggregate possesses so much in common that 

 for it, and especially — most wrongly — for a pronounced part of it, 

 "acid soils," have I used the term "potassic." 



My present word of correction would emphasize the importance 

 of our local workers' studying the problem of soil-preferences of 

 plants, and giving us just the information which my papers 

 intended to give. The ideal Local Flora of the future will 

 present a classification of the flora into sub-floras and associations, 

 accounting for the distinctness of each type; also it must give 



