Oedbr 155.— CTPERACE^. ^737 



5 E. trioostata, Torr. Culm flUrorm, flattened, striato, 1 to 2f high; spike cylin- 

 dric-oblong, 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 

 promicent, thiclc angles, l-oughish, brown, crowned with a whitish, minute tuber- 

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



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

 pa,le green, several of them fruitless; stesi/s truncate ; spOce 3 — 12" long, scarcely 

 thicker than the stem, placed 2 — 5'' below its apex ; girnnes 3 — 9, linear-lanceo- 

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

 long, pale brown; fefiercte closely sessile. — Ponds and ditches, N". H. and Mass. 

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

 as hairs. Jl. 



7 E. oapitkta Brown. Culm filiform, furrowed, angular, 4' to 6', in tufts ; spike 

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

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

 lens-shaped, black, shining, oi-jwaed with a minute, depressed tubercle ; style 2- 

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



8 E. albida Torr. Culm filiform, terete, striate, sulcate on one side, 8 to 12'' 

 spilce 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 ; style 3-oleft. — Wet, sandy places, Ga., Ma. to La. Known 

 at sight by its whitish heads. Sheaths very short. 



9 E. olivacea Torr. Guhns ccespitous, 2 — i' high, slender, subcompressed, sul- 

 cate, soft; spilce ovate, aoiitish, 2 — 3" long, 20 — 30-fiowered ; glumes ovate, ob- 

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

 bristles 6; sty. 2-clcft; a^h. broadly obovate, smooth, of a dull, blackish-olive 

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

 Mass. to Ga. 



10 E. tenuis Schultes. Culm almost filiform, quad/rangular, the sides sulcate, 

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

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

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

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



11 E. obti^sa Schultes. Culm sulcate, subterete, 6 — 15' high; spiJce ovoid, very 

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

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

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

 and U. S., common. Jl. 



12 E. tuberculosa R. Br. Culm columnar, striate, 12' high, leafless, sheathed 

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

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

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

 able for its large tubercle. Jl. 



13 E. simplex Torr. Culm 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- 

 oleft. — Wei places, N. Car. to Pla. and La. 



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

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

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

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

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

 bristles.— R. I. (Olney), N. Y. (Sartwell), to Mich. 



15 E. melanocdrpa Torr. Culm oompressBi, {mrowei, slender, almost filiform, 

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

 length, 20— 40-flowered; glumes ovate, obtuse, brownish, with scarious margins 

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

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



16 E. compressa Sullivant. Cufoi 12 — 18' high, csespitous, much compressed, 



47 



