52 



1J inches long and loosely flowered 5 the spikelets are two-flowered ; 

 the outer glumes are about two lines long, the lower one one-nerved, 

 the upper rather obovate and three-nerved ; the lower flower is com- 

 monly awnless or only tipped with a short awn; the second flower is 

 rather shorter and with a slender, spreading awu longer than the flower. 

 This is a nutritious grass, but is seldom found in sufficient quantity 

 to be of much value. (Plate 55.) 



Trisetum subspicatum. 



The culms are erect and firm, smooth or downy. The panicle is spike-like, dense, 

 and cylindrical or elongated, and more or less interrupted, generally of a purplish 

 color. The spikelets are two or three-flowered. The flowers are a little longer than 

 the outer glumes, slightly scabrous, the flowering glumes acutely two-toothed at the 

 apex, and bearing a stout awn which is longer than its glume. 



A perennial grass of the mountainous region of Europe and North 

 America; undoubtedly furnishes a considerable portion of mountain 

 pasturage. It is found sparingly in New England, on the shores of 

 Lake Superior, in the Eocky Mountains of Colorado, Utah, California, 

 Oregon, and northward to the Arctic circle. It varies in height accord- 

 ing to the latitude at which it grows, being sometimes reduced to 3 or 

 4 inches, at other times running up to 2 feet high. (Plate 56.) 



AVENA. 

 Avena fatua (Wild Oats). 



This species is very common in Calfornia. It is generally thought to 

 have been introduced from Europe, where it is native, but it has become 

 diffused over many other countries, including Australia and South 

 America. It is thought by some to be the original of the cultivated 

 oat, Avena sativa, that the common will degenerate into the wild oat, 

 and that by careful cultivation and selection of seed the wild oat can 

 be changed into the common cultivated oat. But on this question there 

 is a conflict of opinions, and the alleged facts are net-sufficiently estab- 

 lished. The wild oat differs from the cultivated one chiefly in having 

 more flowers in the spikelets, in the long, brown hairs which cover the 

 flowering glumes, in the constant presence of the long, twisted awn, 

 and in the smaller size and lighter weight of the grain. It is a great 

 injury to any grain-field in which it may be introduced; but for the 

 purposes of fodder, of which it makes a good quality, it has been much 

 employed in California. (Plate 57.) 



ARRHENATHERUM. 



Arrhenatherum avenaceum (Evergreen Grass; Meadow Oat Grass; Tall Oat Grass). 

 Culms 2 to 4 feet high, erect, rather stout, with four or five leaves each ; the sheaths 

 smooth, the leaves somewhat rough on the upper surface, 6 to 10 inches long, and about 

 3 liues wide, gradually pointed. The panicle is loose, rather contracted, from 6 to 10 

 inches long, nnd rather drooping; tint branches very unequal, mostly in fives, the 

 longer ones 1 to 3 inches, and subdivided from about the middle; the smaller branches 

 very short, all rather full-flowered. The spikelets are mostly on short pedicels. The 



