26 BULLETIN UNITED STATES GEOLOGICAL SURVEY. [VolVL 



On the eastern plains they are the characteristic feature. When w< 

 beyond the eastern prairie border, the grasses of which are prevailingly 

 eastern in character, we come upon plains which arc generally covered 

 with the very low and tufted grasses peculiar to the drier plains, which 

 form, if not a sward, yet something which serves as a substitute for it> 

 not green, except in early spring, but of a dull grayish hue, and the 

 characteristic species usually rising only a hand-breadth above the sur- 

 face. These are the Buffalo Grasses or Bunch Grasses, which have 

 nourished hordes of bison and flocks of antelopes down to a few years 

 ago, and which are now the capital of the herdsmen or ranchmen, and 

 the nutritious food of increasing numbers of domestic cattle. 



The Buffalo Grass, par excellence, and by its abundance, is Buchloe 

 dactyloides of Engelmann. This is a dioecious Chlorideous grass, the 

 male and the comparatively scarce female plants of which were very 

 naturally thought to be of quite different genera until their relation- 

 ship was suspected and determined by Dr. Engelmann, and this apt 

 name was applied to it. 



Munroa squamosa of Torrey (Crypsls squarrosa, Nutt.), another much 

 depressed and peculiar Chlorideous grass, is next in importance. Both 

 are wholly peculiar to this region. 



Bouteloua, a Chlorideous genus of a more ordinary type, of several 

 species, chiefly endemic to this region and to corresponding districts in 

 Mexico, is the third in rank. These are the " Grama" Grasses — a name 

 which probably came from the Spanish. They are taller, of sparser 

 growth, and make good forage. 



Pleuraphis Jamesi, Torr., is a Buffalo Grass peculiar to the southern 

 part of the region, with some westward extension. 



Vaseya comata, Gray, represents another peculiar genus; but the spe- 

 cies extends to the Calif ornian region. 



Eriocoma cuspidata is the Bunch Grass of the very driest soils, and 

 naturally extends across the Great Basin. 



Sporobolus airoides, Torr., abounds over the whole length of the region 

 and beyond it, in the more low and subsaline soils. It is accompanied 

 by Beckmannia (also a Xorth Asiatic grass), by Distichlis maritime . by 

 one or two wide-spread species of Atropis, &c. The drier ground in 

 many places bears species of Stipa and ArisUda. Hordeum jubatum and 

 the peculiar Elymus sit union are characteristic grasses. 



Of other dominant and more or less peculiar forms of vegetation — hav- 

 ing chiefly in view the central tract — we should mention a great white- 

 flowered Argemone [A. Itisj>i<la, Gray); Stanleya, and the greater part of 

 the known species of Vesicaria; Oleome mtegrifoUa ; the whole genns 

 Call h- rh <>'r ; a Krameria; a Glycyrrhuta; the herbaceous 8ophora sericea; 

 the principal development of the peculiar genns PeUUosteman^ and south- 

 ward onmerons species of Dalea (which goon increasing into Mexico ; 

 also of Psoralea ; most of the species of Qauroj several of (Enothera, and 

 the peculiar genus Sft nosiphon, allied to Gaura ; a good number of Cac- 



