268 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



Figure 525.— Distribution of 

 Hordeum nodosum. 



Figure 527.— Distribution of 

 Hordeum pusiaum. 



6. Hordeum adscendens H.B.K. (Fig. 530.) Annual; culms 

 geniculate at base, 20 to 50 cm tall; spike erect, 3 to 6 cm long ex- 

 cluding awns; glumes all reduced to awns, scabrous, mostly 1.5 to 



2 cm long, somewhat 

 spreading, the awn of the 

 fertile floret as long as 

 the glumes. O — Dry 

 open ground, Arizona and 

 and Mexico. 



7. Hordeum murinum 

 L. Mouse barley. 

 (Fig. 531.) Annual; 

 culms bushy-branched, spreading; sheaths and blades smooth; spike 

 5 to 7 cm long, often partially enclosed by the uppermost inflated 

 sheath; glumes of the central spikelet narrowly fusiform, 3-nerved, 

 long-ciliate on both margins, the nerves scabrous, 

 the awn about 2.5 cm long; glumes of 

 the lateral spikelets unlike, the inner 

 similar to the central ones, the outer 

 setaceous, not ciliate; lemmas all 

 broad, 8 to 10 mm long, the awns 

 somewhat exceeding those of the 

 glumes. © — Fields, waste places, 

 and open ground, introduced from 

 Europe ; here and there in the Eastern 

 States from Maine to Alabama; com- 

 mon on the Pacific coast, Idaho and 

 British Columbia, south to Utah, New 

 Mexico, and California (fig. 532). 



8. Hordeum vulgare L. Barley. 

 (Fig. 533.) Annual; culms erect, 60 

 to 120 cm tall; blades flat, mostly 5 

 to 15 mm wide; spike erect or nearly 

 so, 2 to 10 cm long, excluding awns; 

 glumes divergent at base, narrow, nerveless, gradually passing into a 

 stout awn; awn of lemma straight, erect, mostly 10 to 15 cm long. 

 O — Cultivated for the grain, sometimes spontaneous in fields and 

 waste places but not persistent. There are two 

 groups of the cultivated barleys. In the 2- 

 rowed forms (H. distichon L.) the lateral spike- 

 lets are fairly well developed but sterile. The 

 probable ancestor for at least a part of these is 

 H. spontaneum Koch, of Asia. In the second 

 group all the spikelets produce large seed. 

 These are called 6-rowed (H. hexastichon L.) or, 

 if the lateral florets overlap, 4-rowed barleys 

 (in European literature). In some varieties the carj^opsis is naked. 

 The ancestor of the 6-rowed barleys is not known but probably was 

 similar to some of our cultivated varieties of this group. Hordeum 

 vulgare var. trifurcatum (Schlecht.) Alefeld, beardless barley. 

 Awns suppressed or converted into irregular short lobes or teeth, 



Figure 526.— 

 Hordeum pusil- 

 lum,Xi. (Hitch- 

 cock 11102, S. 

 Dak.) 



Figure 528. — Hordeum 

 gussoneanum, X 1. 

 (Hitchcock 2688, Calif.) 



Figure 529.— Distribution of 

 Hordeum gussoneanum. 



