178 CYPERACEAE 



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

 0.5-2 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. Scirpus Hallii 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 dSbilis 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 

 blade : 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 Americanus 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 swamps, 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. 



