PREFACE. 
The following account of the flora of the State of Washington, by 
Prof. C. V. Piper, is based on his study of the plants of that State 
during a period of twenty years. This work was carried on in chance 
hours of leisure and in occasional summer vacations. During most 
of the college year 1899-1900, however, Professor Piper was at the 
Gray Herbarium looking up critical material and examining the 
specimens of older collectors, especially those upon which publications 
had been based. Considerable time was devoted also to other large 
herbaria, particularly those of the United States National Museum, 
of the Academy of Natural Sciences of Philadelphia, and of the 
New York Botanical Garden. The private herbaria of Prof. L. F. 
Henderson, of Mr. Thomas Howell, and of Mr. W. N. Suksdorf were 
likewise freely consulted. 
Most of the types of the new species published by Professor Piper 
in the present work and in earlier papers are in the United States 
National Herbarium, and a large part of the whole material on which 
this flora is based is also represented there. 
In the course of his work Professor Piper examined specimens of 
nearly all the collections made within the confines of the State of 
Washington, so far as these are to be found in American herbaria. 
Thus it was possible to ascertain the identity of nearly all the species 
which had been accredited to the State through erroneous determi- 
nation. Unfortunately several of the specimens upon which the 
names in published lists were based are not now to be found in 
the herbaria in which they might be expected. This is true particu- 
larly of Cooper’s plants and in less degree of those of the Wilkes 
Expedition, so that the identity of such plants can only be surmised. 
In publications on the collections of Menzies, Douglas, Scouler, and 
Tolmie there are many plant names that can be definitely rectified 
only by examining the original specimens. It is quite certain also 
that the current interpretation of a number of species based on these 
early collections is erroneous. Their correction will require an exam- 
ination of the types, which are in European herbaria. 
With few exceptions no species has been admitted into this flora 
unless its author has actually studied Washington specimens. 
In the course of the preparation of this work Professor Piper be- 
came indebted to many botanists for assistance. He states that he 
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