138 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



68. Poa juncifolia Scribn. Alkali 

 bluegrass. (Fig. 181.) Pale; culms 

 erect, 50 to 100 cm. tall; ligules short, 

 those of the innovations not visible 

 from the sides; blades involute, 

 smooth, rather stiff; panicle narrow, 

 10 to 20 cm. long, the branches ap- 

 pressed; spikelets 3- to 6-flowered, 7 

 to 10 mm. long; glumes about equal; 

 lemmas about 4 mm. long. % (P. 

 brachyglossa Piper.) — Alkaline mead- 

 ows, Montana to British Columbia, 

 south to South Dakota, Colorado, and 

 east of the Cascades to northeastern 

 California. 



69. Poa ampla Merr. Big blue- 

 grass. (Fig. 182.) Green or glaucous; 

 culms 80 to 120 cm. tall; sheaths 

 smooth, rarely scaberulous; ligule 

 short, rounded; blades 1 to 3 mm. 

 wide; panicle narrow, 10 to 15 cm. 

 long, usually rather dense; spikelets 

 4- to 7-flowered, 8 to 10 mm. long; 

 lemmas 4 to 6 mm. long. 91 — 

 Meadows and moist open ground or 

 dry or rocky slopes, North Dakota to 

 Yukon Territory, south to Nebraska, 



Figure 182. — Poa ampla. Panicle, X 1; floret X 10. 

 (Crandall 205, Colo.) 



New Mexico, and California. The 

 typical form is robust and more or 

 less glaucous; this grades into a 

 smaller green form, more common in 

 the eastern part of the range (P. con- 

 fusa Rydb.). Occasional specimens of 

 the typical form have short rhizomes. 



13. BRIZA L. Quaking grass 



Spikelets several-flowered, broad, often cordate, the florets crowded and 

 spreading horizontally, the rachilla disarticulating above the glumes and 

 between the florets; glumes about equal, broad, papery-chartaceous, with 

 scarious margins; lemmas papery, broad, with scarious spreading margins, 

 cordate at base, several-nerved, the nerves often obscure, the apex in our 

 species obtuse or acutish; palea much shorter than the lemma. Low annuals 

 or perennials, with erect culms, flat blades, and usually open, showy panicles, 

 the pedicels in our species capillary, allowing the spikelets to vibrate in the 

 wind. Standard species, Briza media. Name from Greek, Briza, a kind of grain, 

 from brizein, to nod. 



The three species found in this country are introduced from Europe. They 

 are of no importance agriculturally except insofar as B. minor occasionally 

 forms an appreciable part of the spring forage in some parts of California. 

 B. maxima is sometimes cultivated for ornament, because of the large showy 

 spikelets. 



Panicle drooping; spikelets 10 mm. wide 1. B. maxima. 



Panicle erect; spikelets 4 to 5 mm. wide. 



Plants perennial; upper ligule 1 mm. long; spikelets about 5 mm. long.... 3. B. media. 



Plants annual; upper ligule 5 mm. or more long; spikelets about 3 mm. long. 



2. B. MINOR. 



1. Briza maxima L. Big quaking 



grass. (Fig. 183.) Annual; culms more, 10 mm. broad, the pedicels 



erect or decumbent at base, 30 to 60 slender, drooping; glumes and lemmas 



cm. tall; panicle drooping, few-flow- usually purple- or brown-margined, 



ered; spikelets ovate, 12 mm. long or O — Sometimes cultivated for orna- 



