POACEAE. 25 



tapering to the apex, slightly scabrous on the upper surface and 

 margins; spikes 2-5 cm. long, nearly 1 cm. broad; rachis angular, 

 pubescent, branches short, 1- or rarely 2-flowered; setae 8-12, spread- 

 ing, 5-10 mm. long, unequal, slender, finely antrorsely scabrous; 

 spikelets ovate, acute, 2-2.5 mm. long; first glume about ^-f as 

 long as the spikelet, ovate, acute, 5-7-nerved; third glume equaling 

 the flowering glume, 5-nerved, subtending a broad palea of its own 

 length; flowering glume elliptic-ovate, finely transversely rugose; 

 palea plane or concave above. 



Frequent along irrigating ditches. Los Angeles; Santa Ana; San 

 Bernardino. 



7. CENCHRUS L. Bur-grass. 



Annual or perennial grasses with usually flat leaves 

 and spike-like inflorescence. Spikelets subtended by a 

 spiny involucre, which is deciduous at maturity with 

 them. Glumes 4, the first hyaline, the second and third 

 membranous, the latter sometimes subtending a palea 

 and staminate flower, the fourth chartaceous, subtending 

 a palea of similar texture which incloses a perfect flower. 

 Stamens 3. Grain free, enclosed in the glume. 



1. C. tribuloides L. Culms erect or decumbent from an annual 

 root, usually robust, 15-45 cm. high, freely branching; sheaths gen- 

 erally very loose, compressed smooth; leaves 6-10 cm. long, 4-8 mm. 

 wide; spikes 25-50 mm. long; involucres crowded on the scabrous 

 rachis, globose, pubescent except at the base, spines stout; spikelets 

 2-flowered, about 6 mm. long. 



Occasional in orchards and gardens. San Bernardino, Parish; 

 Rialto. Native of Europe. 



Tribe 3. PHALARIDEAE. Canary-grass Tribe. 



Spikelets more or less laterally compressed, 1 -flowered 

 or rarely 3-flowered; glumes 5, the first 2 empty and 

 below the articulation of the rachilla, the third and 

 fourth above the articulation, usually empty or rarely 

 subtending staminate flowers, very unlike the other ones, 

 sometimes reduced to bristles, the fifth glume with a 

 1-nerved or nerveless palea and a hermaphrodite flower. 



Represented with us by the single genus. 8. Phalaris. 



8. PHALARIS L. Canary-grass. 



Annual or perennial grasses with flat leaves and 

 spike-like, capitate or narrowly paniculate inflorescence. 



