180 CYPERACEAE 



very slender, sometimes 1.5 dm. long, spreading or drooping : spikelets mostly solitary at 

 the ends of the raylets, 6-12 mm. long, 1 mm. thick : scales ovate, greenish brown : peri- 

 anth-bristles 6, flexuous, shorter than the scales : stigmas 3 : achenes 3-angled, not papil- 

 illose, nearly white, not shining. 



In swamps, Virginia and Kentucky to Missouri, Florida and Louisiana. Summer. 



19. Scirpus fontin&lis Harper. Kelated to S. divaricatus and S. lineatus; differing 

 from both of these species by its curved stem and lateral umbels, from the former by its 

 thicker spikelets and papillose achenes and from the latter by its merely acute scales and 

 shorter perianth-bristles. 



On margins of pools, Leslie, Georgia. Summer. 



20. Scirpus line&tus Michx. Perennial by stout rootstocks. Stems triangular, 3-10 

 dm. high : leaf-blades 4-8 mm. wide, flat, rough-margined : umbels decompound, the rays 

 very slender, becoming pendulous : spikelets mostly solitary at the ends of the raylets, 6-10 

 mm. long, about 2 mm. thick : scales ovate or oblong, reddish brown and each with a green 

 midvein : perianth-bristles 6, weak, smooth, entangled, much longer than the achene : stig- 

 mas 3 : achenes oblong or oblong-obovoid, 1 mm. long, pale brown, 3-angled, short-beaked. 



In swamps and wet meadows, New Hampshire to Ontario, Oregon, Georgia and Texas. Summer. 



21. Scirpus cyperinus (L. ) Kunth. Perennial. Stems smooth, stiff, 6-20 dm. tall : 

 leaves elongated ; blades 3-6 mm. wide, rough-margined : bracts of the involucre 3-6, the 

 longer much exceeding the inflorescence : umbel terminal, compound, the rays at length 

 somewhat drooping : spikelets ovoid-oblong, 3-5 mm. long, in capitate clusters of 3-15 at 

 the ends of the raylets : scales ovate or lanceolate : perianth-bristles 6, entangled, smooth, 

 much longer than the achene, much exserted beyond the scales, and grayish brown at 

 maturity : stigmas 3 : achenes 3-angled, barely 1 mm. long, beaked, nearly white. 



In swamps, Newfoundland to Ontario, Virginia and Tennessee. Summer and fall. 



22. Scirpus Eriophorum Michx. Similar to the next preceding species in habit. 

 Involucre more ferruginous at the base : umbel with laxer branches, the rays elongated 

 and drooping at the ends: spikelets ovoid or oblong-ovoid, 3.5-6 mm. mostly 4.5 mm. 

 long, more deeply colored, at least some of them distinctly peduncled. 



In low grounds or swamps, New York to Arkansas, Florida and Texas. Summer and fall. 



23. Scirpus Cub6nsis Poepp. & Kunth. Perennial, glabrous. Scapes sometimes 

 tufted, 2-7 dm. tall, sharply 3-angled : leaves basal ; blades 3-5 mm. wide : bracts of the 

 involucre mostly 3-5, spreading : spikelets crowded into 1 or several very dense subglobose 

 heads, about 12-flowered, 3-5 mm. long: scales 4 firm, 13-nerved, each with a short spread- 

 ing tip, commonly ciliate along the keel : perianth-bristles wanting : stigmas 2 : achenes 

 elliptic or slightly broadest below the middle, 2-2.5 mm. long, tapering into a slender beak. 



In swamps, Alabama and Louisiana. Also in the West Indies, eastern South America and Africa. 

 Summer and fall. 



9. WEBSTERIA S. Hart Wright. 



Perennial caulescent aquatic herbs, with repeatedly branching stems. Leaves clustered, 

 capillary. Umbel decompound. Bracts of the involucres similar to the leaves. Spikelets 

 1 -flowered, peduncled : scales 2 to each spikelet, the lower one sterile. Flowers perfect. 

 Perianth of 6-10 commonly barbed nearly white bristles. Stamens 3. Style slender, de- 

 ciduous above the base : stigmas 2. Achene lenticular, minutely pitted in lines. 



1. Websteria subme'raa (Sauv. ) Britton. Submersed, glabrous. Stems 3-12 dm. 

 long, with internodes 8-25 cm. long, sheathed, the branches topped by decompound umbels : 

 spikelets 8-12 mm. long : scales acuminate, the lower one 3-nerved within, empty, the 

 upper 1 -nerved, with reddish brown margins : perianth-bristles tortuous : achenes lenticu- 

 lar, obovoid or oval, about 1.5 mm. long, each tipped with the base of the style. [Scirpus 

 submersus Sauv. Websteria limnophila S. Hart Wright. ] 



In lakes and ponds, peninsular Florida. Also in Cuba. Spring to winter. 



10. ELEOCHARIS K. Br. 



Annual or perennial scapose herbs. Leaves reduced to sheaths, or the lowest very 

 rarely blade-bearing. Scapes simple, triangular, quadrangular, terete, flattened or grooved. 

 Spikelets solitary, terminal, erect, several-many-flowered, not subtended by an involucre 

 or rarely by 2 small bracts. Scales concave, spirally imbricated. Perianth of 1-12 bristles, 

 usually retrorsely barbed, wanting in some species. Stamens 2-3. Stigmas 2 and achene 

 lenticular or biconvex, or when 3, the achene 3-angled, but sometimes with very obtuse 



