MANUAL OF THE GRASSES OF THE UNITED STATES 



97 



Keels of palea awned about one-third from the base, the awns 2 to 7 mm. long. 



5. P. OREGONUS. 



Keels of palea awnless. 



Lemmas awnless or mucronate, thick, firm, strongly nerved 4. P. davyi. 



Lemmas awned, the awns 1 to 12 mm. long. 



Lemmas 4 to 6 mm. long, firm, strongly nerved; wings of palea split about half way to 

 the base forming 2 prominent teeth; culms mostly 30 to 60 cm. tall. 



1. P. CALIFORNICUS. 



Lemmas 8 to 9 mm. long, relatively thin, the nerves evident but not prominent; culms 

 mostly more than 1 m. tall. 

 Spikelets reflexed or spreading; awn of the lemma 5 to 12 mm. long. 



2. P. REFRACTUS. 



Spikelets erect or ascending; awn of the lemma 1 to 2.5 mm. long. 



3. P. HOOVERIANUS. 



1. Pleuropogon californicus (Nees) 



Benth. ex Vasey. (Fig. 109.) Annual; 

 culms tufted, erect or decumbent at 

 base, 30 to 60 cm. tall; blades flat or 

 folded, seldom more than 10 cm. long, 



2 to 5 mm. wide; raceme 10 to 20 cm. 

 long, with 5 to 10 rather distant 

 short-pediceled spikelets; spikelets 6- 

 to 12-flowered, mostly about 2.5 cm. 

 long, erect, or somewhat spreading; 

 glumes obtuse, erose, 4 to 6 mm. long; 

 lemmas scabrous, 5 to 6 mm. long, 

 the nerves prominent, the tip obtuse, 

 scarious, erose, the awn usually 6 to 

 12 mm. long; wings of palea promi- 

 nent, cleft, forming a tooth about the 

 middle. O — Wet meadows and 

 marshy ground, Mendocino County 

 to the San Francisco Bay region, 

 California. 



2. Pleuropogon refractus (A. Gray) 

 Benth. ex Vasey. Nodding sema- 

 phoee-grass. (Fig. 110.) Perennial; 

 culms 1 to 1.5 m. tall; blades elon- 

 gate, the uppermost nearly obsolete, 



3 to 7 mm. wide; raceme mostly 15 

 to 20 cm. long, the spikelets as many 

 as 12, about 3 cm. long, 8- to 12- 

 flowered, finally reflexed or drooping; 

 lemmas about 8 mm. long, subacute, 

 less scabrous and the nerves less 

 prominent than in P. californicus; 

 awn 5 to 12 mm. long; palea narrow, 

 keeled to about the middle, scarcely 

 or minutely toothed. % — Bogs, 

 wet meadows, and mountain streams, 

 Washington to Mendocino County, 

 Calif., west of the Cascades. 



3. Pleuropogon hooverianus (Ben- 

 son) J. T. Howell. (Fig. 111.) Similar 

 to P. refractus, but the spikelets erect 



Figure 110. — Pleuropogon refractus. Plant, X 1; 

 floret, X 5. (Sandberg and Leiberg 734, Wash.) 



or ascending; lemmas toothed at the 

 broader hyaline summit, the awn 1 

 to 2.5 mm. long; wings of palea with 

 a single pointed tooth 1 to 1.5 mm. 

 long; rachilla joints swollen and 

 spongy toward the base. % — 

 Grassy wooded flats, Mendocino and 

 Marin Counties, Calif. 



4. Pleuropogon davyi Benson. (Fig. 

 112.) Culms erect from short slender 

 rhizomes, 60 to 100 cm. tall; sheaths 



