Graminaceae 51 
above the glumes, shorter, thin, hyaline, finely pointed or shortly bifid, awned or the 
lower sometimes awnless; awn fine, dorsal, twisted, arising below the middle. Pallet 
hyaline, nearly as long as its lemma. Stamens 3. Grain more or less adherent. (Gk. 
aira—a deadly weapon; applied to a poisonous darnel. ) 
A. Panicle loose and spreading; leaf-sheaths mostly much shorter than the internodes. 
A. caryophyllea L. (Silvery Hair-grass) 
AA. Se aicle dense, spike- ikewe: nearly so; leaf-sheaths almost as long as the inter- 
nodes. W. A. praecox L. (Karly Hair-grass) 
ARRHENATHERUM 
Perennial, tall. Leaf-blades flat. Spikelets 2-flowered, in a loose terminal erect 
often |-sided panicle; the lower flower staminate, the upper perfect or pistillate; rachilla 
hairy, jointed below the lower flower, produced into a straight point or bristle above the 
upper one. Glumes unequal, persistent, acute, thin, scarious on the margins, keeled. 
Lemma thinly scarious, 5—7-veined, apex slightly dentate; the lower with a dorsal 
twisted geniculate awn attached near the base; the upper unawned, or with a minute 
awn near the apex, or with a dorsal twisted awn. Palet hyaline, ciliate on the veins. 
Stamens 3. Grain ovoid, not furrowed, free. (Gk. arren—masculine, ather—awn; only 
the staminate flower is awned.) W. 
A, elatius Beauv. (Tall Oat-grass) 
DESCHAMPSIA HAIR-GRASS 
Annual or perennial, tufted. Spikelets 2—3-flowered, shining, in a_ terminal 
panicle; panicle loose, or rarely contracted; rachilla hairy, more or less prolonged beyond 
the upper palet. Glumes keeled, rarely acute, the sides thinly scarious. Lower flowers 
sessile; upper one stalked. Lemma membranous or nearly hyaline, 4-veined, obtuse or 
truncate, 2—4-toothed, awned; awn fine, dorsal, arising at or below the middle. Palet 
narrow, often 2-toothed. Stamens 3.: Grain usually free. (Honor of J. C. A. Loise- 
feur-Deslongchamps, a French botanist. ) 
A. Some of the flowers projecting beyond the glumes; awn very slightly or not at all 
projecting beyond its lemma. W. E. 
D. caesp*tosa Beauv. . (Tufted Hair-grass) 
AA. Flowers not projecting beyond the glumes; awn projecting beyond its lemma once 
the lemma-length or more. . | 
B. Perennial; glumes 3—6 mm. long; awn either less than 6 mm. long or straight, 
or both. 
C. Leaf-blades flat; awn hardly or not at all projecting beyond the glumes; 
glumes |-veined, 4.5—-6 mm. long; plants 1.5—4 dm. high. W. C. E. 
D. atropurpurea Scheel (Mountain Hair-grass) 
CC. Leaf-blades rolled up; awn projecting beyond the glume at least V4 the 
glume-length; glumes 3-veined, 3—4 mm. long; plants 3—12 dm. high. W. 
CGE: D. elongata Mun. (Slender Hair-grass) 
BB. Annual; glumes 6—8 mm. long; awn 6—12 mm. long, geniculate. E. 
ae ea ee ES = D, calycina Presl. (Oat-like Hair-grass) 
TRISETUM FALSE OAT 
Perennial, tufted. Spikelets 2——5-flowered, in a panicle; panicle narrow or 
spreading, loose or dense; rachilla jointed, hairy or smooth, more or less elongate between 
the flowers, extending beyond the upper fertile flower either as a hairy bristle or bearing 
