-'^ ■ GRAMINACEAE (GRASS FAMILY) 41 



BB. Leaf blade scabrous; lemma broadly oval; awn 3-5 mm. long. E. — A good 

 range grass. O. cuspldata (indian millet) 



AA. Lemma hairs when present not dense nor conspicuous; panicle narrow (except 

 0. kingii); alpine (except 0. kingii). 

 C. Awn of lemma 3-4. mm. long. C. E. O. exigua (small mountain rice) 



CC. Awn of lemma 10-15 mm. long. 

 D. Alpine; rays of panicle bearing 2-4 spikelets each; lemma smooth. E. 



O . hendersonl 



DD. Not alpine; rays of panicle bearing 1-2 spikelets each; lemma with short 



hairs on lower half. E. O. kingii 



PHLEUM (Timothy) 



Perennial, erect. Leaf blades flat. Spikelets flat, in a dense cylindric 

 or ovoid spike. Glumes almost equal, membranous, compressed-keeled, 

 1-3-veined, abruptly pointed, the keel projecting as a point or awn. Lemma 

 shorter and wider than the glumes, thin, hyaline, truncate or denticulate, 

 awnless, 5-veined, inclosing the palet. Palet nearly equaling the lemma, 

 narrow, hyaline. Stamens 3. Grain ovoid, free. — (Gk. phleos = somQ 

 kind of reed.) 



A. Spikes 1.5-3 cm. long; awn of glume 2 mm. long; plant 2-6 dm. high. W. C. E. 



P. alpinum (mountain timothy) 



AA. Spikes 3-17 cm- long; awn of glume i mm. long; plant 4-10 dm. high. W. E. 



— One of the best and most common hay grasses, P. pratense (timothy) 



AVENEAE (Oats Tribe). — Spikelets in either open or spikelike panicles, 

 ^ to several flowered. Rachilla produced beyond the upper lemma (except 

 in Air a). Glumes 2. Lemma with tuft of hair at base, some in each spikelet 

 awned (except Trisetum muticum) ; awn either dorsal or near the apex be- 

 tween the lobes. Palet 2-keeled. Stigmas plumose. 



A. Plants 2 dm. high or less; spikelets 2-flowered,-both perfect; rachilla jointed below 

 the glumes, not prolonged beyond the upper flower. — (Gk, aira = a deadly weapon; 

 applied to a poisonous Darnel.) Aira (hair grass) 



AA. Plants mostly taller; spikelets 2- to several-flowered, sometimes only i perfect 

 when only 2; rachilla jointed above the glumes (except in Holcus), prolonged be- 

 yond the upper flower. 

 B. Plants densely soft-whitish-hairy; spikelets falling off entire; rachilla jointed 

 below the glumes; spikelets 2-flowered, the lower perfect, the upper staminate; 

 awn of second flower hooklike. W. E. — A common grass especially west of the 

 Cascades, often cut for hay. It often crowds out other and better hay grasses 

 and then becomes a weed. Sometimes wrongly called " Mesquite." (Gk. holkos 

 = some kind of grass.) Holcus lanatus (velvet grass) 



BB. Plants not densely soft-whitish-hairy; spikelets falling off in parts; rachilla 

 jointed above the glumes; spikelets 2- to several-flowered (2 only in Arrhenaiherum, 

 which has the perfect flower above); awns not hooklike. 

 C. Spikelets i cm. long or less. 

 D. Spikelets 8-10 mm. long; lemma awned from near the base; spikelets only 

 2-flowered; upper flower perfect or pistillate, the lower staminate. W. — (Gk. 

 arren = masculine, atker = an awn; only the staminate flowers are awned.) 



Arrhenatherum elatius (tall oat -grass) 



