PREFACE. 



Under direction of the Board of Trustees, the twentieth 

 annual report of the Missouri Botanical Garden is presented 

 to the pubUc. 



The nineteenth report was issued November 9, 1908, but 

 the following papers contained in it had been previously 

 issued in separate form at the dates indicated: — Bessey, The 

 Florida StrangUng Figs, March 4; Sargent, Crataegus in 

 Missouri, July 2. 



As in the tenth report, an index to the contents of the 

 last ten volumes has been included in the present volume. 



These reports are sent to scientific institutions and jour- 

 nals, in exchange for publications and specimens desirable 

 for the library, herbarium or living collections of the Garden. 

 So far as is possible, reprints of the botanical articles they 

 contain are sent to botanists occupied with a study of the 

 subjects to which they pertain. 



Any of the Garden publications not out of print may be 

 purchased, at approximately the cost of publication, from 

 Messrs. R. Friedlandcr & Sohn, Berhn, Germany; W. Wesley 

 & Son, London, England; or the undersigned. 



William Trelease. 



St. Louis, Mo., November 1, 1909. 



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