GRIFFITHS — THE GRAMA GRASSES. 345 



cutting for hay. In the main the nutritious and valuable herbage 

 of the grama grasses consists of their basal leaves, and these grasses 

 are consequently adapted mainly to grazing. 



In the main the perennial species very well withstand heavy grazing 

 and the abuses incident to the open range method of handling stock. 

 Indeed, there are few if any grasses that are superior to them in this 

 regard. Bouteloua gracilis is the species of prime importance in the 

 prairie region, and, together with B. chondrosioides, B. filiformis, B. 

 radicosa, etc., is also important upon the higher lands farther south. 

 No recorded experiences upon the behavior of these plants under crop- 

 ping systems in the Southwest are known except the general observa- 

 tion that too close grazing reduces the vitality of the plants, and, if 

 long continued, kills them out entirely (PI. 68, A). Upon the northern 

 prairies many observations have been made upon the behavior of the 

 prairie grasses when cut for hay. The extent and degree of cropping 

 have been much more definitely observed in the prairie region. In 

 the Dakotas, Bouteloua gracilis withstands grazing very well, but if 

 grazed closely for even one season it takes it two or three years to 

 recover. It is the common experience that hay can not be cut on 

 the upland prairies oftener than once every two years. In other 

 words, the removal of the ground cover of one year's growth, as close 

 as the mower takes it, sets the plant back at least one year, while 

 burning is still more detrimental. But this applies to the prairie 

 grasses in general. 



ADAPTABILITY TO CULTIVATION. 



Many efforts have been made to cultivate the different species of 

 Bouteloua, especially during the grass-garden period of experimenta- 

 tion in this country, from about 1892 to 1900. 



The most promising of all the species for field cultivation is B. 

 curtipendula (PI. 69, A), not that it grows any more readily than 

 the others, but on account of its size and habit. All the species re- 

 spond readily to cultural treatment, but none of them have a good 

 seed habit, a very important characteristic in an agricultural grass. 

 The seed can not easily be even properly thrashed. All that can be 

 done is to strip off the spikes, which separate readily from the panicle 

 upon maturity. The whole spike has been invariably sown. In 

 B. gracilis and allied forms the spikelets readily separate from the 

 spikes, but even here it would be impracticable to attempt to secure 

 clean seed. 



Explanation of Plate 68.— A. A region in which about half a dozen species of Bouteloua grow in pro- 

 fusion whenever summer rains are seasonable, in spite of the fact that it is continuously closely grazed. 

 B. Scene in the Santa Rita Mountains, Arizona. Bouteloua curtipendula and tall forms of B. hirsuta and 

 B. radicosa predominate, mixed with species of Leptochloa, Andropogon, Heteropogon, Muhlenbergia 

 and Panicum. 



Explanation of Plate 69. — A. Bouteloua curtipendula. B. Bouteloua gracilis. Both growing at 

 Walla Walla, Washington. Photographs by Leckenby. 



