GENERA OF GRASSES OF THE UNITED STATES. 93 
37. ELymMusS 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. Pl. 83, 1758; 
Gen. Pl., ed. 5,36. 1754. Lin- 
nzus describes five species, H. 
arenarius, E. sibiricus, H. can- 
adensis, FE. virginicus, and E. 
caput-medusae, all of which 
are still retained in the genus. 
The first use of the name Ely- Fic. 46.—Scribneria bolanderi. Plant, X 4; spike- 
mus by Linneus was in his let with joint of rachis, x 5; the same, front 
Hortus Upsaliensis (1748), view, X 5. 
where two species are de- 
scribed, the first being cited in the Species Plantarum under ZH. virginicus 
the second under #. sibiricus. Hlymus 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. Midl. 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? considers them to be developed 
from lateral branches at the base of the spikelet. Schuster? states 
that the first or outer glume originates as a single organ but soon 
1PRot. Jahrb. Engler 40: 97-113, 1907. 
?Flora 100: 213-266, pl. 2-5. 1910. 
