334 



GRASS ORDER 



SCIRPUS Linne 1753 BULRUSH, CLUB RUSH 



(Lat. name of the bulrush) 



PL 44, fig. 16, 17. 



Spikelets solitary or in umbels, spikes or heads, usually with a 1-sev- 

 eral-leaved involucre ; flowers perfect, scales spirally imbricated all around ; . 

 perianth-bristles 1-6 or occasionally none, stamens 2-3, style 2-3-cleft ; leaves 

 long-linear or often reduced to sheaths ; annual or perennial. 



1. Spikelet solitary and terminal 



a. Stems 3-angled, grooved, 2-8 in. high ; scales 



lanceolate, long-pointed ; bristles 2-6, spiny ; 



achenes gray, finely netted S. paucifiorus 



b. Stems round, 4-15 in. high; scales ovate, ob- 



tuse; bristles 6, smooth; achenes brown, not 



netted v$\ caespitosus 



2. Spikelets more than 1 as a rule, usually several- 



many, often lateral 



a. Spikelets 1-12 in a dense, head-like cluster 



(1) Stems round; leaves channelled or revo- 



lute; bristles 1-3, not half as long as the 



achene 6". nevadensis 



(2) Stems triangular 



(a) Involucral leaves of head 1 



x. Scales awned ; leaves 1-3 5. americdnus 



y. Scales short-pointed ; leaves usually 



mere sheaths 5. Glneyi 



(b) Involucral leaves 2-3 



x. Bristles usually 2, twice as long as the 



achene S\ pahidosus 



y. Bristles 1-3, less than half as long as the 



achene, or none 5 1 . campestris 



b. Spikelets many, in panicles or umbels 



(1) Stems round, leafless; cluster lateral; 



Spikelets 5-15 mm. long; bristles 4-6, 

 barbed, as long or longer than the 

 achene 5. lacustris 



(2) Stems triangular, leafy; cluster terminal 



(a) Spikelets 15-25 mm. long; scales with a 



long, curved awn 



(b) Spikelets 4-10 mm. long; scales without 



a curved awn S. fluvidtiUs 



