178 CYPERACEAE 



4. Scirpus carinktus (H. & A. ) A. Gray. Annual, bright green. Scapes tufted, 

 0.5-'^ dm. tall, bristle-like, smooth : leaves solitary at the base of each scape, bristle-like : 

 bracts of the involucre 1-3 cm. long, erect : spikelets solitary, ovoid, about 4 mm. long, 

 apparently lateral, 6-8-flowered : scales ovate to reniform, acuminate, loosely imbricated, 

 keeled, rather persistent : stigmas 3 : achenes 3-angled, oval, 1.5 mm. long, brown, gran- 

 ular. [Isolepis carinata H.. & A.] 



In low grounds, Tennessee to the Indian Territory, California, Alabama and Texas. Spring. 



5. ScirpuB Hdllil A. Gray. Annual. Scapes very slender, smooth, tufted, obtusely 

 triangular, erect, striate, 1-3 dm. tall : lower sheaths oblique, and acuminate or mucronate, 

 the upper one commonly bearing a filiform blade 1-6 cm. long : spikelets capitate in clusters 

 of 1-7, oblong-cylindric, obtuse, many-flowered, 6-12 mm. long, about 2 mm. thick, ap- 

 pearing lateral by the extension of the solitary involucral bract : scales ovate-lanceolate, 

 light greenish brown, acuminate, keeled, cuspidate : perianth-bristles wanting : achenes 

 obovoid-orbicular or slightly broader than high, black, plano-convex, mucronulate, trans- 

 versely wrinkled, about 1 mm. in diameter. 



In wet soil, Massachusetts to Florida, Illinois, Colorado, Texas and Mexico. Summer and fall. 



6. Scirpus d6bilis Pursh. Annual, smooth : scapes slender, terete or nearly so, tufted, 

 1.5-5 dm. high : sheaths obliquely truncate, the upper ones rarely bearing a short subulate 

 tlade : spikelets capitate, in clusters of 1-12, ovoid-oblong, subacute, many-flowered, ap- 

 pearing lateral, the involucral bracts narrowly linear, 3-10 cm. long, erect or divergent : 

 scales light yellowish brown with a green midvein, broadly ovate, obtuse, or acute : peri- 

 anth-bristles 4-6, downwardly barbed, about as long as the achene : stigmas 2 or rarely 3 : 

 achenes plano-convex, broadly obovoid or orbicular, 1.5-2 mm. long, smooth or slightly 

 roughened, dark brown, shining, obtuse, mucronulate. 



In wet soil, Maine to Ontario, Minnesota, Georgia, Alabama and Nebraska. Summer. 



7. Scirpua Americ^nus Pers. Perennial by long rootstocks. Scapes sharply trian- 

 gular, erect, stiff, 3-11 dm. tall : leaves 1-3 ; blades linear, keeled, shorter than the scape : 

 spikelets oblong-ovoid, acute, 8-12 mm. long, capitate in clusters of 2-7, appearing as 

 if lateral : involucral bract slender, 3-10 cm. long : scales broadly ovate, brown, often 

 emarginate or sharply 2-cleft at the apex, the midvein extended into a subulate awn some- 

 times 2 mm. long, the margins scarious : perianth-bristles 2-6, downwardly barbed, shorter 

 than or equalling the achene : achenes obovoid, plano-convex, about 2.5 mm. long, smooth, 

 dark-brown, mucronate. 



In fresh water and brackish swamps, nearly throughout North America. Summer. 



8. Scirpus Olneyi A. Gray. Similar to the next preceding species. Scapes stout, 

 sharply 3-angled, with concave sides, 0.5-2 m. tall : leaves 1-3, 2-13 cm. long, or repre- 

 sented by mere sheaths : spikelets capitate in dense clusters of 5-12, oblong or ovoid-ob- 

 long, obtuse, 5-8 mm. long, the involucral bract short, stout, erect, 1-3 cm. long : scales 

 oval or orbicular, dark brown with a green midvein, emarginate or mucronulate, glabrous : 

 perianth-bristles usually 6, slightly shorter than or equalling the achene, downwardly 

 barbed: stigmas 2 : achenes obovoid, about 2.5 mm. long, plano-convex, brown, mucro- 

 nate. 



In salt marshes, Massachusetts to Florida, Texas, Mexico and California, extending along the 

 Pacific coast to Oregon. 'Also in Arkansas. Summer and fall. 



9. Scirpus cylindricus (Torr. ) Britton. Perennial by stout rootstocks. Scapes 

 stout, 3-angled above, 1-2 m. high, the linear nodulose keeled dark green leaves nearly or 

 quite as long : involucral bract 1-2.5 dm. long, erect : spikelets in an apparently lateral 

 umbel, drooping, oblong-cylindric, acutish, 1-2 cm. long, primary rays of the umbel sub- 

 tended by 1 or more subulate-linear bracts : scales ovate or ovate-lanceolate, pale-brown, 

 acute, mucronulate : perianth-bristles 6, stout, rigid, about as long as the achene, serrate : 

 stigmas 3 : achenes obovoid, 3 mm. long, excluding the beak, 3-angled, light brown, smooth, 

 abruptly subulate-pointed. 



In ponds and swamjis, Maryland to Florida and Lousiana. Summer and fall. 



10. Scirpus lacustris L. Perennial by rootstocks. Scapes stout, terete, smooth, 

 erect, 1-3 m. tall, sometimes 2 cm. in diameter, sheathed below : involucral bract soli- 

 tary, erect, shorter than the umbel : umbel compound, appearing lateral, its primary rays 

 3-10 cm. long : bracts linear-lanceolate : spikelets becoming oblong-cylindric, in mostly 

 capitate clusters of 2-5, sessile or some of them peduncled, 5-16 mm. long, 3-4 mm. in 

 diameter : scales ovate or oblong, each with a strong midvein which is sometimes excur- 

 rent : perianth-bristles 4-6, downwardly barbed, equalling or longer than the achene : 

 stigmas 2 : achenes plano-convex, obovoid, 2-2.5 mm. long, gray, abruptly mucronate, dull. 



In ponds and swamps, nearly throughout North America. Also in the Old World. Summer and 

 fall. Cat-tail Flag. 



