PREFACE. 



The present paper consists of the first instaUment of an account of 

 the trees and shrubs of Mexico, by Mr. Paul C. Standley, Assistant 

 Curator of the United States National Herbarium. The work is 

 based wholly upon the extensive series of Mexican plants in the 

 National Herbarium, a large proportion of which have been secured 

 by special investigators sent out by the United States National 

 Museum and the United States Department of Agriculture. The 

 flora of Mexico, especially the arborescent flora, includes many 

 species of gi-eat economic value. They furnish many products of 

 commercial importance, such as henequen and ixtle fiber, palm oil, 

 lumber, cacao, rubber, drugs, alcohol, and various kinds of fruits. 



Heretofore no descriptive flora of any portion of tropical conti- 

 nental North America has been published, and the identification of 

 the species of plants yielding important products has often been very 

 difficult. Identification of material has been possible only by com- 

 parison with extensive series of herbarium specimens, such as are to 

 be found only in the larger botanical institutions, or by reference to 

 isolated descriptions, many of these available only in the largest 

 libraries. The work of which the present paper is the first installment 

 brings together all the published species of woody Mexican plants, 

 and furnishes keys for their identification, as well as brief descriptive 

 notes. Much information is presented also concerning commercial 

 and local uses of the plants. The vernacular names of the trees and 

 shrubs are given, and since these are fairly well standardized by 

 local usage, they will be found helpful as guides to the identity of 

 fragmentary or otherwise difficult material. 



The account of the ferns of the families Gleicheniaceae and 

 Cyatheaceae has been furnished by Mr. William R. Maxon, Associate 

 Curator of the National Herbarium ; that of the Poaceae, or grasses, 

 by Prof. A. S. Hitchcock, Systematic Agrostologist of the Depart- 

 ment of Agriculture ; and that of the Amaryllidaceae, which includes 

 Ihe difficult genus Agave, or century plants, by Dr. William Trelease, 

 Professor of Botany, University of Illinois. 



Frederick V. Coville, 

 Curator of the United States National Herbarium. 



