vi Acknowledgments 



Brown, Willard O. Youngs, and Miss Wanda Z. Brockman of 

 the Seattle Public Library, and Miss Florence Waller, for- 

 merly of that institution, have aided our researches in the 

 literature. Finally we acknowledge our great indebtedness 

 to Mr. and Mrs. Carl S. English, Jr., botanists, for much in- 

 formation as well as a critical reading of the whole manu- 

 script; and to Robert B. Hitchman for his constant and 

 helpful criticism during the preparation of each chapter and 

 the final assembly. 



To all of these and to many others whose names are not 

 mentioned we are truly grateful. 



HARRY W. HIGMAN 

 EARL J. LARRISON 



