410 Bulletin No. 205 [March, 



Agropyron violaceum. — This species is reported by Hiictt ( '97, 

 131), but no specimens have been seen. 



60. HORDEUM L. 

 Barley 



In this genus the inflorescence consists of terminal spikes, the spike- 

 lets in groups of three at each joint of the axis. The axis of the spike 

 disjoints with the spikelets attached to the joints. The central spike- 

 let of the group bears perfect florets, but the two lateral ones may be 

 reduced to awns. In cultivated barley we have the two-rowed variety 

 when only the middle spikelet of each group is perfect, and the six- 

 rowed when all are perfect. The glumes are often reduced to awns 

 and together with the sterile lateral spikelets form a cluster of awns 

 below the spikelet. The leaves are flat, usually with well-developed 

 membranous ligules. Besides the cultivated barley, H. vulgare, four 

 other species are found in the state, two of which are pernicious weeds. 



Spikes slender, not over 3 inches long, the awns of the spikelets not over 15 mm. 

 long. 



Glumes modified into slender awns. i7. nodosum 



Glumes narrow, broadened in the middle, awn-pointed. H. pusillum 



Spikes rather stout, with awns 20 to 60 mm. long. 



Awns 30 to 60 mm. long, making a spike about as wide as long; spikelets 



1-ilowered. H. juhatum 



Awns 20 to 35 mm. long, the width of the spike less than one-third its length ; 



spikelets 2-flowered, with often a rudiment of a third. H. iwmmeli 



Hordeum jubatum L. 



Squirrel-tail Grass (Figs. 273 and 275) 



Lapham '57, 547, 586 (Plate 3, Fig. 9); Babcock 73, 97; Patterson 76, 51; 

 Flagg 78, 282; Brendel '87, 64; Higley and Eaddin '91, 147; Huett '97, 131; 

 Sherff '13, 595. 



Culms in large bunches, 6 inches to 2 feet tall, usually erect, some- 

 times bent at base, the spikes nodding ; sheaths smooth ; blades 1 to 5 

 inches long, 2 to 4 mm. wide, rough ; spike 2 to 4 inches long ; spike- 

 lets in threes, the lateral ones imperfect and reduced to 1 to 3 spread- 

 ing awns; glumes of the perfect spikelets awn-like, and spreading; 

 lemmas 6 to 8 mm. long, awned ; awns of the spikelets all long, slender, 

 and rough. 



Tbis species is a biennial and in Illinois often a winter annual. It 

 is (me of the worst weeds of the state, not only because it crowds out 

 useful plants, but because the awns are very troublesome to live stock. 

 Any scheme of cultivation that prevents its ripenir.g seed will control 

 it. It is, however, more apt to come up in pastures and waste places 

 which cannot well be cultivated, and as it ripens a large number of 

 seeds, it may spread very rapidly. 



