44 CYPERACEAE 



Bristles not barbed. 



Bristles shorter than or scarcely exceeding the 



scales. 5. 8. lineatus. 



Bristles much exserted beyond the scales when 



mature. 6. 8. cyperinus. 



1. S. Americanus Pers. Perennial with a sharply 3-angled culm : 

 spikelets 1-7, appearing lateral, the single involucral leaf seeming to be 

 a continuation of the culm : spikelets oblong-ovoid, 3 // -4 // long, the 

 scales short-awned : achene plano-convex. Wet places at Courtney and 

 Sheffield. May-July. 



2. S. lacustris L. A stout perennial, 3-9 high : umbel appearing 

 lateral, compound, usually many-flowered : spikelets about 4" long and 

 \\ ff broad, ovate-oblong : scales mucronate-tipped : bristles barbed : 

 acheue plano-convex, white. Common in all ponds, and often along 

 rivers. May-September. 



3. S. fluviatilis (Torr. ) A. Gray. Culms sharply 3-angled, 3-6 tall : 

 culm leaves Q // -8 // wide : spikelets sessile, or sessile and crowded at the 

 ends of the raylets : the raylets 5-9 and often 5' long : acheue triangular. 

 Locally common in ponds, Sheffield, Lake City. May-July. 



4. S. atrovirens Muhl. Culms 2-4 high, 3-angled : spikelets brown- 

 ish in dense capitate clustsrs, in a terminal compound umbel : spikelets 

 6-20 together, l // -3 // long : scales sharp-pointed : bristles 6, downwardly 

 barbed above : achene triangular. In bogs and low grounds in north- 

 eastern part. June- July. 



Var. pallidus Britton. Spikelets greenish-brown, 20-75 together in 

 the capitate clusters. Common in damp places throughout. 



5. S. lineatus Michx. Culm triangular, leafy, l-4 high : umbel 

 very compound : spikelets oblong-cylindrical, at length drooping, 2 // -5 // 

 long : bristles 6, smooth at maturity, barely if at all exceeding the acute 

 scales. Common in wet woods or prairies. May-June. 



6. S. cyperinus (L. ) Kunth. A stout perennial, 2-5 high : umbel 

 very compound : spikelets ovoid-oblong, \\ ff -%\" long : bristles at ma- 

 turity much exceeding the scales and very conspicuous, rust-colored. In 

 a bog along the foot of the bluffs three-fourth of a mile east of Courtney. 

 June-July. 



8. PUIRENA Rottb. 



Culms triangular, leafy. Spikelets in axillary and terminal clusters. 

 Scales imbricated all around, awned. Perianth of three cordate-ovate 

 or ovate-oblong scales on claws, alternating with as many downwardly 

 barbed bristles. Stamens three and styles 3-cleft. Achene triangular, 

 tipped with the non-swollen persistent base of the style. 



1. F. simplex Vahl. A hairy tufted perennial, 10' high : leaves 

 !'-!$' long, l"-2" wide, with loose sheaths : spikelets 3"-6" long : 

 scales recurved-awned : perianth scales notched at apex, cordate at 



