6 PKEFACE. 



is under especial obligations to Prof. B. L, Robinson, of the Gray 

 Herljariiim, for kindly counsel, as well as for much aid in the genus 

 Lupinus; to Mr. Frederick V. Coville, of the National Herbarium, 

 for his continuous helpful advice; to Dr. N. L. Britton, of the 

 New York Botanical Garden, Mr. Stewardson Brown, of the Acad- 

 emy of Sciences of Philadelphia, and Dr. C. F. Millspaugh, of the 

 Field Columbian Museum, for the privileges of consulting the her- 

 baria of which they have charge; to Mr. M. L. Fernald, of the Gray 

 Herbarium, for technical assistance in various genera; to Dr. J. M. 

 Greenman, of the Field Columbian Museum, for aid in Senecio; to 

 Mr. A. A. Faton, for a key to the species of Isoetes; to JMr. P. L. 

 Ricker and Mr. W. F. Wight, of the Department of Agriculture, 

 for assistance in bibliograpiiy ; to Dr. Theodor Holm and Prof. C. F. 

 A\lieeler for aid in the genus Carex. 



Thanks are extended to the many persons who have favored Pro- 

 fessor Piper with their collections of Washington plants, especially 

 Mr. Kirk Whited, of Wenache, Washington ; Prof. R. M. Horner, of 

 Waitsburg, Washington; Prof. J. B. Flett, of Tacoma, Washington, 

 and Mr. M. W. Gorman, of Portland, Oregon. 



For the privilege of examining their private herbaria Professor 

 Piper is indebted to Mr. Thomas Howell, of Milwaukee, Oregon ; to 

 Mr. W. N. Suksdorf, of Bingen, Washington, and to Prof. L. F. Hen- 

 derson, of Moscow, Idaho. 



Frederick V. Coville, 

 Curator of the United States Nat tonal Ilertxtrhnn. 



