114 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 
49. Ama LL. 
(Deschampsia Beauv.) 
Spikelets 2-flowered, disarticulating above the glumes, the, hairy 
rachilla prolonged behind the upper floret as a stipe, this sometimes 
i bearing a reduced floret; glumes‘about equal, acute 
\ or acutish, membranaceous; lemmas thin, truncate 
Si y and 2 to 4 toothed at the summit, bearing a slender 
: Ny ~ awn from or below the middle, the awn straight, bent, 
NOC ‘or twisted. 
Ny) j = ee Low or moderately tall 
annual or usually peren- 
nial grasses, with shining 
>) ann pale or purplish spikelets 
f \. In narrow or open pani- 
l/ ~~ cles. Species about 35, in 
~ the temperate and cool 
regions of both hemispheres, 6 of these 
being in the United States. 
A\ 
aly, 
\S \\ WW 
Type species: Aira caespitosa L. 
Aira L., Sp. Pl. 68, 1753; Gen. Pl., ed. 5, 31. 
1754. Fourteen species are described. The 
name was first used for a genus by Linnzeus 
in his Flora Lapponica in 1737, where he 
describes four species. These four species 
are named in the Species Plantarum: 7. A. 
spicata, 8. A. caespitosa, 9. A. flexuosa, 10. 
A. montana. The first of these, A. spicata, 
is referred to Trisetum; the other three be- 
long to Deschampsia, as recognized in most 
‘American botanies. The genus Aira, as 
accepted by Bentham and Hooker in the 
Genera Plantarum and by Hackel in the 
Natitirlichen Pflanzenfainilien, is based upon 
the last two of the original Linnean 
Fie, 59.—Tall oat-grass, Arrhenatherum elatius. Plant, Xx 43 spikelet and fertile floret, 
x 5. 
