GENERA OF GRASSES OF THE UNITED STATES. 



93 



37. ELYMUS L. 



Spikelets 2 to 6 flowered, sessile in pairs (rarely 3 or more or soli- 

 tary) at each node of a continuous rachis, the florets dorsiventral to 

 the rachis; rachilla disarticulating above the glumes and between the 

 florets; glumes equal, usually rigid, sometimes indurate below, nar- 

 row, sometimes subulate, 1 to several nerved, acute to aristate, some- 

 what asymmetric and often placed in front of the spikelets ; lemmas 

 rounded on the back or 

 nearly terete, obscurely 

 5-nerved, acute or usually 

 awned from the tip. 



Erect, usually rather tall 

 grasses, with flat or rarely 

 convolute blades and ter- 

 minal spikes, the spikelets 

 usually crowded, some- 

 times somewhat distant. 

 Species about 45, in the 

 temperate regions of the 

 Northern Hemisphere; 25 

 species in the United 

 States, most of them in 

 the Western States. 



Type species : Elymus sibiri- 

 cus L. 



Elymus L., Sp. PI. 88, 1753 ; 

 Gen. PI., ed. 5, 36. 1754. Lin- 

 naeus describes five species, E. 

 arenarius, E. sibiricus, E. can- 

 adensis, E. virginicus, and E. 

 c<i put-medusae, all of which 

 are still retained in the genus. 

 The first use of the name Ely- 

 mus by Linnaeus was in his 

 Hortus Upsaliensis (1748), 

 where two species are de- 

 scribed, the first being cited in the Species Plantarum under E. virginicus 

 the second under E. sibiricus. Elymus 'sibiricus is chosen as the type because 

 it is the first of the five species in the Species Plantarum that is described in 

 the Hortus Upsaliensis. 



Terrellia Lunell, Amer. Midi. Nat 4: 227. 1915. Proposed for Elymus L., 

 not Elymus of various ancient authors. 



The asymmetric glumes, in many species standing in front of the 

 spikelet instead of strictly distichous and in some species united at 

 the very base, have been the object of investigations as to their 

 morphological identity. Schenck 1 considers them, to be developed 

 from lateral branches at the base of the spikelet. Schuster 2 states 

 that the first or outer glume originates as a single organ but soon 



FIG. 46. Scribneria bolanderi. 

 let with joint of rachis, X 

 view, X 5. 



Plant, X I ; spike- 

 5 ; the same, front 



iRot. Jahrb. Engler 40: 97-113. 1907. 

 3 Flora 100: 213-266, pi. 2-5. 1910. 



