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PKKFACE. 



The present volume of the Contributions from the United States 

 National ITerbariuni consists of seven papers. 



The first paper, by Charles V. Piper, ^^ North American Species of 

 Festuca,'' was prepared in the Office of the Agrostolo<,nst, Department 

 of Agriculture, but in view of the fact that it was of a strictly sys- 

 tematic — not agricultui-al — character, it was offered to the National 

 ^Museum for publication and was accepted. The author of the manu- 

 script regrets that it was not possible to consult all the type specimens 

 of the American species, several of which are in European herbaria, 

 but he considers it preferable to oflfer his work for puldication now 

 rather than to delay it indefinitely. 



The second paper, entitled ^^'I1se Gomis Ptelea in the AVestern and 

 Southwestern United States and Mexico," by Dn Edward L, (rreene, 

 Associate in Botany, United States National Museum, is the result of 

 an exhaustive study of the western spet^ics of Ptelea. Doctor Greene 

 finds that this genus, instead of l)eing composed of only a few species, 

 is a very large one, and describes 59 species, of which 55 are new. 



His work is based chief! v 



on the large series of 



specimens m 



the 



National Herbarium, in his own collection now deposited here, and in 

 Capt. John Donnell Smith's, eventually to come here, together with 

 the collections of the late C. C. Parry and that of the California 

 Academy of Sciences. The typos are chiefly in the National 

 Herbarium, and urdcss otherwise indieatt^I are to be understood as 

 belonging here. 



The third paper ('onsists of the fifth number of ''Studies of Mexi- 

 can and Central American Plants,'^ by Dr, J. N. Rose, Associate 

 Curator, Division of Plants, United Sfcites National Museum. Doctor 



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resulted in 



the acquisition of a valuable collection for the National Herbarium 

 and in a published report. Kac^h of these reports, like the accom- 

 panying one, covers only fragmentary portions of his whole work. 

 All, however, are devoted to the elucidation of the .larae general 

 subject, the flora of central Mexico, and together they form a highly 

 valuable series of contrilmtions to our botanical knowledge of that 



Tlie fouitli paper i,s "The Lt^gumino.sae ol; Torto Kico," by Miss 

 Janet Russell Perkins, Pb. D. In 1901 and 1902 Miss Perkins, under 



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