PREFACE. 
By authority of the Board of Trustees, the eleventh 
annual report of the Missouri Botanical Garden is presented 
to the public. 
The tenth report was issued June 5, 1899. Separates of 
the following papers contained in the present volume were 
issued on the dates noted: Von Schrenk, A disease of Tax- 
odium, etc., June 3, 1899; Rose, Agave expatriata, etc., 
June 3, 1899; Norton, A revision of the American species 
of Euphorbia of the section Tithymalus, etc., July 10, 1899; 
Smith, Revision of the species of Lophotocarpus, etc., Sep- 
tember 27, 1899. 
These reports are sent to scientific institutions and jour- 
nals, in exchange for publications and specimens desirable 
for the library, herbarium, or collection of living plants of 
the Garden. So far as possible, reprints of the botanical 
articles they contain are sent to botanists occupied with a 
study of the subjects treated. Any of the Garden publica- 
tions not out of print may be purchased, at approximately 
the cost of publication, from the Cambridge Botanical Sup- 
ply Co., Cambridge, Mass.; A. I. Eriksson, Tufts College, 
Mass.; R. Friedlinder & Sohn, Berlin, Germany; W. 
Wesley & Son, London, England, or the undersigned. 
Wma. TRELEASE. 
St. Louis, Mo., Jan. 10, 1900. 
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