PREFACE. 
Under direction of the Board of Trustees, the seven- 
teenth annual report of the Missouri Botanical Garden is 
presented to the public. 
The sixteenth volume was issued on May 31st, 1905, 
which is to be regarded as the date of publication of the 
scientific papers it contains, except that by Professor 
Hitchcock, separates of which were distributed on March 
29th, 1905. 
These reports are sent to scientific institutions and 
journals in exchange for publications or specimens desir- 
able 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 pur- 
chased at approximately the cost of publication from Mess. 
R. Friedlinder & Sohn, Berlin, Germany; W. Wesley & 
Son, London, England, or the undersigned. 
Witiram TRELEASE. 
St. Louis, Mo., October 10, 1906. 
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