INTRODUCTION. 



The region of country immediately adjoining the northern boundary of Mexico, 

 including the western part of Texas, and the greater part of New Mexico, Arizona, 

 and southern California, is one of remarkable heat and aridity. It is mainly a 

 region of elevated plains, called mesas, intersected by mountain ranges which occa- 

 sionally run into high peaks, and is drained by comparatively few streams, which, 

 on account of the limited rain-fall, cease to flow during a good part of the year, or 

 convey only the waters obtained from distant portions of the country. 



Most of the region lies north of the thirty-second parallel of latitude, and in the 

 western part reaches into Utah and Nevada. It is with great propriety called the 

 desert belt. The country northward, and east of the Rocky Mountains, as far as 

 the one hundredth meridian, is an elevated arid plain, but with more abundant 

 grasses, although rarely forming a continuous and connected sod. 



In the desert belt, however, the grasses become scanty, not in variety of species, 

 but in distribution, some of them being short-lived, springing up suddenly after the 

 summer rains and rapidly maturing ; others perennial, growing in bunches, and 

 having deeply penetrating roots which enable them to endure the long droughts of 

 the country. Nowhere do the native grasses form a continuous sod, but grow in 

 scattered bunches in connection with the low bushes which prevail on the mesas or 

 among the chaparral. 



The country embraced in this desert belt is an extension northward of the 

 great plateau of northern Mexico, as is shown in the similar character of its vege- 

 tation. The grasses are largely the same, or of the same genera. But the grasses, 

 like the rest of the vegetation, are peculiar to the region. Here one never sees the 

 common grasses of the Eastern States. The vegetation is as different from that 

 of the Eastern States as is that of the northern portion of the Sahara. Hence 

 arises the utility of bringing to the notice of the public, and especially of the 

 residents of this region, the information contained in this work. It is not a manual 

 or description of all the grasses of the region, but it furnishes illustrations and de- 

 scriptions of some of the more interesting and some of the commoner grasses of the 

 country. Many of them were observed and specimens collected by the naturalists 

 of the Mexican Boundary Survey, and by those of the Pacific Railroad Survey, but 

 few or none of these have heretofore been illustrated or fully described. True, the 

 descriptions here given are mostly in technical language, but accompanied by the 

 illustrations they afford the best possible means of recognition. Probably the most 

 important agricultural question before the people of this region is how to increase 

 the production of grasses and forage plants on the arid lands. It is the opinion of 

 many that this can be done by bringing under cultivation some of the native species. 

 Experiments are about to be undertaken in this direction by the Agricultural Ex- 

 periment Stations and by individuals. The first step in such an enterprise is a 

 knowledge of or an acquaintance with the native species. Nothing can be better 

 adapted to this object than the work here undertaken, and in this way the knowl- 

 edge of the scientist can be made helpful to the practical economist. In this first 

 part of the work fifty plates of grasses are given. A second part of an equal num- 

 ber of plates is now in preparation, after which it is proposed to publish an analyti- 

 cal synopsis of all the grasses of the desert region. The drawings of the grasses 

 have been made chiefly by Mr. William R. Scholl, and in the description of the 

 species I wish to acknowledge important aid from Mr. Frederick V. Coville, Assist- 

 ant Botanist. 



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