﻿PREFACE. 



Under direction of the Board of Trustees, the eighteenth 

 annual report of the Missouri Botanical Garden is presented 

 to the public. 



The seventeenth volume was issued on November 6th, 

 1906, which is to be regarded as the date of publication of 

 the scientific papers it contains, except that by Dr. Spaulding, 

 separates of which were distributed on August 31st, 1906, 

 and those by Dr. Hedgcock, separates of which were dis- 

 tributed on September 27th, 1906. 



These reports are sent to scientific institutions and journals 

 in exchange for pubhcations or specimens desirable for the 

 Garden, and, when possible, reprints of the botanical articles 

 they contain are presented to botanists occupied with a study 

 of the subjects they refer to. Any of the Garden publications 

 not out of print may be purchased at approximately the cost 

 of publication from Mess. R. Friedlander & Sohn, Berlin, Ger- 

 many; W. Wesley & Son, London, England; or the undersigned. 



William Trelease. 



St. Louis, Mo., Oct. 10, 1907. 



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