POACEAE. 65 



acute, or those of the lowest floret sterile and subulate, entire 

 with a single awn, or trifid and three-awned. 

 This genus is hardly distinct from Elymus. 



Glumes 2-nerved; inflorescence 2-8 mm. long. 



Awns of lemmas 3-4 cm. long. S. rigidum. 



Awns of lemmas 4-5 cm. long. S. glabrum. 

 Glumes 3-5-nerved; inflorescence 10-15 cm. long. 



Leaves glaucous, 5-8 mm. broad. 5. planifolium. 



Leaves green, 2-5 mm. broad. 5. rubescens. 



Sitanion rigidum J. G. Smith. Stems 10-20 cm. high; leaf blades green 

 or slightly glaucous, rigid, 2-5 mm. wide, flat or at length involute; spike 

 green, 2-8 cm. long, erect or nearly so, often included at base in the upper 

 sheath; glumes or glume divisions 4 and entire or 6, that is the lateral ones 

 divided to the base, all awned; lemma 7-9 mm. long, tipped with a stout awn 

 3-4 mm. long. 



In rocky soil in the mountains at 2000-2500 m. altitude. 



Sitanion glabrum J. G. Smith. Pale or somewhat glaucous, tufted; leaves 

 flat, 2-5 cm. wide; spike 5-8 cm. long; glumes bifid, 6-8 cm. long. 

 Dry rocky places in the mountains, at high altitudes. 



Sitanion planifolium J. G. Smith. Tufted, 50-60 cm. high, more or less 

 glaucous; leaf-blades 5-8 mm. wide, flat, glabrous; spike suberect, purplish, 

 6-9 cm. long; glumes 6-7 mm. long, entire or bifid, tipped with an awn about 

 2 cm. long; lemma 10 mm. long, lancolate, minutely scabrous, bearing an awn 

 3-4 cm. long. 



Olympic Mountains, Elmer; Mount Adams, Suksdorf. 



Sitanion rubescens Piper. Stems tufted, 50-70 cm. high; leaves flat; 

 spikes erect, flexuous, 10-15 cm. long, purplish; glumes 4, entire or rarely 

 bifid, 3-nerved; lemma tipped with a slender awn about 4 cm. long. 



Dry rocky slopes of Mount Rainier. 



Family 17. CYPERACEAE. Sedge Family. 

 Grass-like or rush-like herbs; stems slender, solid (rarely 

 hollow), triangular, quadrangular, terete or flattened; leaves 

 narrow with closed sheaths; flowers perfect or unisexual in 

 spikes or spikelets, one in the axil of each scale (glume or bract) ; 

 spikelets solitary or clustered, 1 to many-flowered; scales two- 

 ranked or in a spiral, persistent or deciduous; perianth hypogy- 

 nous, composed of bristles or scales or wanting; stamens 1-3, 

 rarely more; ovary 1 -celled, 1-ovuled; style 2 or 3-cleft; fruit a 

 lenticular or triangular akene; endosperm mealy; embryo minute. 



Flowers unisexual, borne in the same or more com- 

 monly separate spikelets. 94. Carex, 66. 

 Flowers of the spikelets all perfect, rarely partly 

 aborted; spikelets all alike. 

 Spikelets with scales in two ranks. 



Perianth none; spikelets in solitary or urn- 

 belled terminal heads. 95. Cyperus, 81. 

 Perianth of 6-9 bristles; spikelets axillary. 96. Dulichium, 82. 



6 



