HOW TO KNOW THE GRASSES 



5b. Lower floret staminate, with a bent, protruding awn; upper floret 



perfect, with a short straight awn; spikelets 7 — 9 mm. long. Fig. 179. 



TALL OATGRASS ArrhenatheTum elatius (L.) Mert. & Koch 



Perennial; tufted; culms 1 — 1.5 m. tall; leaf 

 blades 5 — 10 mm. wide; panicles narrow and 

 elongated, but with spreading short branches, 

 15 — 30 cm. long; glumes thin and somewhat 

 translucent. Rarely both florets have bent 

 awns. Tall oatgrass is cultivated in the north- 

 ern states as a meadow grass and has freely- 

 escaped to roadsides and waste ground. May 

 — September. Introduced from Europe. 



Figure 1 79 



6a. Awn attached near the base of the lemma 7 



6b. Awn attached above the middle of the lemma or absent 8 



7a. Rachilla prolonged beyond the base of the upper floret as a minute 

 hairy bristle. Fig. 180. 



HAIRGRASS Deschampsia caespitosa (L.) Beauv. 



Perennial; tufted; culms slender, 

 60 — 120 cm. tall; leaves flat and sca- 

 brous, mostly at the base of the 

 plants, 1 — 4 mm. wide; panicles open, 

 dehcate; spikelets often purple. The 

 awns are nearly hidden within the 

 glumes. The lemmas have several 

 minute teeth at their tips. Bogs, wet 

 ground, mountain meadows. An im- 

 portant forage grass in the West. May 

 -July. 



Deschampsia flexuosa (L.) Trin. is 

 similar but the awns are strongly 

 bent and protrude from the spikelets. 

 Leaf blades fine and hair-like. Arc- 

 ^'^""'^ ^^° tic North America, southward to Min- 



nesota and Michigan and southward 

 in the Appalachian Mts. to Georgia; Arkansas and Oklahoma. 



96 



