GENERA OF GRASSES OF THE UNITED STATES. 45 
narrow panicles of cylindric spikelets, the lemmas pubescent below, is 
common at lower altitudes in California. Mutton grass (P. fendleri- 
ana) is important in the Southwest. Little bluegrass (P. sand- 
bergiz), differing from malpais bluegrass in having smooth sheaths, is 
common at medium altitudes (2,000 to 8,000 feet) throughout the 
Northwest. 
9. Briza L., the quaking grasses. 
Spikelets several-flowered, broad, often cordate, the florets crowded 
and spreading horizontally, the rachilla glabrous, disarticulating 
above the glumes and between the florets, the uppermost floret re- 
duced; 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. 
Annual or perennial, low grasses, with erect culms, flat blades, and 
usually open, showy panicles, the pedicels in our species capillary, 
allowing the spikelets to vibrate in the wind. Species about 20, the 
greater number South American. The three species found in the 
United States are introductions from Europe and occur here as 
occasional weeds in waste places. 
Type species: Briza media L. 
Briza L., Sp. Pl. 70, 1753; Gen. Pl., ed. 5, 32. 1754. WLinnseus describes 4 
species, B. minor, B. media, B. maxima, and B. eragrostis. The first three were 
familiar to Linneus as cultivated plants in the Hortus Cliffortianus, and the 
second, which is selected as the type species, was described in his flora of Swe- 
den. The first three species are now retained in Briza, the last is referred to 
Eragrostis. 
Of the three species found in this country, one, Briza media (fig. 
14), is perennial, and two, B. minor and B. maxima, are annual. The 
spikelets of B. maxima, a species sometimes cultivated for ornament 
under the name quaking grass, are large and showy, half an inch long, 
drooping on slender pedicels. Briza minor, with smaller upright 
spikelets, is rather common on the Pacific coast. 
10. Wracrostis Host, 
Spikelets few to many flowered, the florets usually closely imbri- 
cate, the rachilla disarticulating above the glumes and between the 
florets, or continuous, the lemmas deciduous, the paleas persistent; 
glumes somewhat unequal, shorter than the first lemma, acute or 
acuminate, 1-nerved, or the second rarely 3-nerved; lemmas acute 
or acuminate, keeled or rounded on the back, 3-nerved, the nerves 
usually prominent; palea 2-nerved, the keels sometimes ciliate. 
Annual or perennial grasses of various habit, the inflorescence an 
open or contracted panicle. Species more than 100, tropical and tem- 
perate regions; 33 species in the United States, in all except the cool 
or mountain regions. 
