165 



BROMUS COMMUTATUS. 



ScnEADEn. Koch. Parnell. H. Watson. Hooker and Aenott. 



PLATE LV. 



Serrafalcus commutatus, Pablatore. Babington. 



The Tumid Field Brome-Grass. 



Bromus — Food. Commutatus — Changed. 



A somewhat common species, growing in corn-fields and on 

 road-sides. 



Stem upright, circular, smooth, and striated, carrying four or 

 five flat, soft, sharp-pointed leaves, "with striated sheaths, the 

 tipper sheath having an obtuse ragged ligule at its summit. 

 Joints five. Inflorescence usually simple-panicled. Panicle when 

 young upright, when more mature pendant. Branches rough. 

 Spikelets linear-lanceolate, brownish purple, mostly of ten awncd 

 florets. Calyx consisting of two almost equal, broad acute 

 glumes; margin membranous. Upper half of the keels dentate. 

 Outer glume three-ribbed; inner glume seven-ribbed. Florets 

 of two nearly equal-sized palere, the exterior one of basal floret 

 oval, rough, glossy, and somewhat longer than the glumes; 

 seven-ribbed. Inner palca linear-oblong, having two green mar- 

 ginal ribs fringed with white hairs. Stigmas plumose. Length 

 from nineteen to thirty-six inches. Root fibrous and annual. 



Bromus secalinus is more linear and lono-cr. 



