Barker, Henry D.2016-03-092016-03-091923-03https://hdl.handle.net/11299/178115University of Minnesota Ph.D. dissertation. March 1923. Major: Botany. Advisor: Dr. E. C. Stakman, Dr. H. K. Haley 1 computer file (PDF); 70 pages.enBotanyThesis or Dissertation