Obdek 155.— OTPEEAOB^. 131 



5 E. triooatata Torr. Culm filiform, flattened, striate, 1 to 2f high; spika q/lm- 

 drio-oilowj, dense-flowered, 6 to 9" long; glumes ovate, obtuse, rusty brown, with 

 a broad, scarious margin and a green midvein ; bristles ; aoh. obovate, with 3 

 prominent, thick angles, roughish, brown, crowned with a whitish, mmuto tuber- 

 cle ; style 3-cleft. — Wet places, N. J. to Fla. 



6 E. Robbinsii Oakes. Culms clustered, 9 — 25' high, rigid, sharply triangular, 

 pale green, several of them fruitless: sftea</» truncate ; spike 3 — 12" long, scarcely 

 thicker than the stem, placed 2 — 5' below Its apex ; glumes 3 — 9, linear-lanoeo- 

 late, acute, finally brownish ; bristles 6, twice longer than the achenium ; ach. 1" 

 long, pale brown; toJercte closely sessile. — Ponds and ditches, K. H. and Mass. 

 (Ricard). Very distinct. In water a part of the stems are floating and as fine 

 as hairs. Jl. 



7 E. capitata Brown. Culm fihform, farrowed, angular, 4' to 6', in tufts ; spiko 

 globular-ovoid, 2" long, greenish white; glumes 12 to 15, oblong, obtuse; 

 bristles 6, some of them a little exceeding the ach., which is broadly obovate, 

 lens-shaped, black, shining, crowned with a minute, depsessed tubercle ; style 2- 

 oleft. — Wet places, Ga., Fla. to La. 



8 E. dlbida Torr. Culm filiform, terete, striate, suloate on one side, 8 to 12' 

 spike ovoid, acute, 2 to 3'' long; glumes 20 to 30, whitish, ovate, rather acute 

 bristles 6, brown, longer than the chestnut-colored, smooth, broad-ovate ach. 

 tubercle small, acute ; stylo 3-cleft. — ^Wet, sandy places, Ga., Ela. to La. Known 

 at sight by its whitish heads. Sheaths very short. 



9 E. olivacea Torr. Culms iaespitous, 2 — 4' high, slender, subcompressed, sul. 

 cate, soft; spiJce ovaXe, acutish, 2 — 3" long, 20 — 30-flowered ; glumes ovate, ob- 

 tuse, reddish-brown, with soarious edges and a green midvein, the lowest largest; 

 bristles 6; sty. 2-clefl;; ach. broadly obovate, smooth, of a dull, ■ blackish-olive 

 color when ripe. — Sands, generally partly submersed. Providence, E. L (Olney) 

 Mass. to Ga. 



10 E. tenuis Schultes. Culm almost flliform, quadrangular, the sides sulcata, 

 8—15', with a long, purple sheath at base ; spike 2 to 3" long, eiliptic-oval, acute 

 at each end ; glumes dark purple, ovate, obuse, the lower ones larger and empty ; 

 ova. roundish, tapering below, invested with 2 or 3 or sets. — Common in wet 

 places, Can. and U. S. Jn., Jl. 



11 B. obtCisa Schultes. Culm sulcate, subterete, 6 — 15' high; spike ovoid, very 

 obtuse, often nearly globous; glumes 60 to 100, round, dark brown, with whitish 

 margins ; ach. obovate, compressed, smooth, brown, invested with 6 setae as long 

 as the glumes, and crowned with a broad, flat tubercle. — Shallow waters. Can. 

 and TJ. S., common. Jl. 



12 B. tuberculdsa R. Br. Culm columnar, striate, 12' high, leafless, sheathed 

 at base ; spike ovate-lanceolate, acutish, glumes very obtuse, loose ; CKh. somewhat 

 triquetrous, not larger than the sagittate tubercle with which it is crowned ; bristles 

 6, as long as the tubercle. — Sandy swamps, N. Eng. to Flor. and La. Remark- 

 able for its large tubercle. Jl. 



13 E. simplex Torr. Cuhu acutely 3-angled (terete Torr.), filiform, striate, 12 to 

 18'; spike ovoid, acutish; scales ovate, obtuse, whitish with a brown center; 

 bristles 6, rigid, longer than the ach., which is broad-obovate, furrowed length- 

 wise, olive-green, crowned with a large, distinct, conic-beaked tubercle ; style 3- 

 clefl. — Wet places, N. Car. to Fla. and La. 



14 E. rostellata Torr. Culm 15 — 20', clustered, angular and sulcate, slender, 

 almost filiform, rigid ; sheaths obliquely truncate, the lowest blackish at summit ; 

 spike lance-ovate, acute, 3 — 4'' long ; glumes 12 — 20, lance-ovate, smooth, light 

 brown, edge soarious ; bristles 4 to 6, longer than the smooth ach., which is bi- 

 convex, olive-brown, with a confluent, acuminate tubercle, shorter than the 6 

 bristles.— R. L (Olney), N. T. (Sartwell), to Mich. 



15 E. melanocarpa Torr. Culm compressed, furrowed, steefer, almost filiform, 

 wiry, 12 — 18' high; sheaths truncate; spike lance-oblong, rather acute, 4 — 6" in 

 length, 20 — 40-floweved ; glumes ovate, obtuse, brownish, with scarious mai^na 

 and a prominent, yellowish midvein; bristles 3, purple; ach. obovate-turbinate, 

 blackish ; tubercle broad, flat, pointed in the center.— Providence, R. L (Olney). 



16 E. compressa Sullivant. Culm 12 — 18' high, osespitous, much compressed, 



47 



