178 CYPERACEAE 
4. Scirpus carinatus (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 débilis 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. Scirpus Americànus 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 : 
erianth-bristles usually 6, slightly shorter than or equalling the achene, downwardly 
yarbed : 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. Alsoin Arkansas. Summer and fall. 
9. Scirpus cylíndricus (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 em. 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. 
