PREFACE. 
Under direction of the Board of Trustees, the twelfth 
annual report of the Missouri Botanical Garden is pre- 
sented to the public. 
The eleventh report was issued February 3, 1900. 
Separates from the present volume were issued on the dates 
noted: Von Schrenk, A disease of the black locust, Feb- 
ruary 10, 1901; Ferguson, Crotons of the United States, 
February 16, 1901; Toumey, An undescribed Agave from 
Arizona, April 6, 1901; Trelease, A cristate Pellaea, April 
6, 1901; Trelease, A Pacific-slope palmetto, April 16, 1901. 
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, and, when possible, reprints of the botanical 
articles they contain are presented to botanists occupied 
with a study of the subjects these refer to. Any of the 
Garden publications not out of print may be purchased at 
approximately the cost of publication from A. I. Eriks- 
son, Tufts College, Mass.; R. Friedlinder & Sohn, Berlin, 
Germany; W. Wesley & Son, London, England; or the 
undersigned. 
WiLuiaM TRELEASE. 
Sr. Lours, Mo., May 10, 1901. 
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