15 E. melanocarpa Torr. Culm compressed, furrowed, slender, almost filiform, wiry, 12 - 18' high; 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; bristles 3, purple; ach. obovate-turbinate, blackish; tubercle broad, flat, pointed in the center. - Providence, R. I. (Olney).
16 E. compressa Sullivant. Culm 12 - 18' high, casspitous, much compressed, narrowly linear, striate; sheath close, truncate; spike oblong-ovate, 3 - 5" in length, 20 - 30-flowered; glumes ovate-lauceolate, acute, mostly 2-cleft at apex, dark purple on the back, with a broad, scarious margin; bristles 0; ach. obovate-pyriform, shining, minutely punctate, of a light, shining yellow, the minute tuberele fuscous. - Wet places N. Y. to Ill.
17 E. acicularis R. Br. Culm leafless, setaceous, quadrangular, very slender, 3 - 6' high; spike compressed, oblong-ovate, acute, 4 - 8-flowered; glumes ob-tusish, the lowest one larger and empty; ach. obovoid, triangular, striated lengthwise. - Edges of ponds, often partly submersed, U. S. and Brit. Am. Very delicate. June, July.
18 E. pigmaea Torr. Culm 1 - 2' high, setaceous, compressed, sulfate; spikes ovate, compressed, 3 - 6-fld.; gl. mostly empty; bristles 6, longer than the achenium, slender, scabrous backwards; ach. ovate, acute, triangular, smooth, not striate, whitish and shining; tubercle minute. - Sea coast, Mass., to Fla. and La.
19 E. microcarpa Torr. Culm capillary, 4-angled, 5 to 8' long; spike oblong, compressed, 10 to 20-flowered, about 2" long, often proliferous; glumes ovate, acutish, keeled, chestnut brown, the lowest much the largest, bristles 3 to 5, shorter than the achenium which is minute, smooth, whitish, with a very minute tubercle. - Wet places, N. J., also La.
20 E. prolifera Torr. Culms capillary, 4-angled and furrowed, 4 to 12' long, in dense tufts; spike minute, 1 to 2" long, compressed, 4 to 6-flowered; glumes ovate, chestnut brown, with scarious margins, often proliferous, that is, producing new culms instead of flowers; bristles 3 or 4, much shorter than the achenium which is 3-angled and with a broad, depressed tubercle. - Fla.! to La. (Hale). (Chaeto-cyperus Baldwinii Torr.)
6. SCIR'PUS, L. Clue-rush. Bullrush. (Celtic cirs, the general name for rushes.) Glumes imbricated on all sides; perigynium of 3 - 6 bristles, persistent; sty. 2 - 3-cleft, not tubereulate at base, deciduous; achenium biconvex or triangular. - Stems mostly triquetrous, simple, rarely leafless. Spikes solitary, conglomerated or corymbous.
§ Scirpus. Bristles retrorsely denticulate, about equaling the achenium. (*)
* Spike single, terminal, with a short, erect bract at its base....................................
Nos. 1 - 3
* Spikes several or many qustered on each culm, (a)
a Clusters of spikes lateral - on the terete, leafless culm.............................
Nos. 4, 5
- on the triangular culm...................................
a Clusters of spikes terminal, mostly umbellate, (b)
b Glumes lacerately 3-toothed. Spikes large (9 to 12" long)........
Nos. 9, 10
b Glumes entire. - Spikes small (1"/), collected in globular heads...................
Nos. 11, 12
- Spikes small (2 to 3" long), separate..............................
§ Tricophorum. Bristles 6, tortuous, tawny, much longer than the achenium, and exserted. Stem (culm) leafy. Umbel decompound..........................................................
Nos. 14, 15
1 S. planifolius Muhl. Culm ccespitous, leafy at base, acutely and roughly 3-angled, 5 - 10' high; lvs. broad-linear, flat, rough on the margin, equaling the stem; spike oblong-lanceolate, compressed, terminal, 4 - 8-flowered; glumes ovate-mucronate, yellowish; bracts at the base of the spike, cuspidate, outer ones longer than the spike; ach. reddish-brown, invested with 6 bristles longer than itself. - In cold, hard soils, Mass. (Bobbins), N. Y. to Del. June.
2 S. subterminalis Torr. Culm floating, furrowed, inflated, leafy below, 1 to 3f long; lvs. very narrow, almost capillary, 2 to 4f long; spike somewhat terminal (the stem being continued above it in the form of a bract), lanceolate; style 2-cleft; bristles 6. - Streams, etc, Mass. to N. Y., Mich. Aug.
3 S. caespitosus L. Culm cœspitous, round, sheathed at base with numerous rudiment'; of leaves; spikes compressed, terminal; 2 lower glumes involucre-like, as long as the spike; ach. with 6 bristles. - Grows in dense tufts, 4 - 12' high. Spike 4 - 5-flowered, reddish-brown. On the alpine summits of Mts., N. States. Jl.
4 S. debilis Pursh. Culm casspitous, roundish, deeply striate, 9 to 1G' high, with a few subulate leaves at base; spikelets about 3, short-ovoid, sessile, crowded, lateral, the culm continuing a fourth of its length above them, glumes ovate, obtuse, carinate, pale green; ach. obovate, mucronate; bristles 4 or 5. - Borders of ponda and rivulets, N. Eng. to Car. Aug.
5 S. lacustris L. Lake Bullrush. Culm smooth, leafless, filled with a porous pith, 5 to 8/ high, cylindric, tapering above the panicle, and abruptly ending in a short cusp; panicle cymous near the top; ped. rough, twice compound; spikelets ovoid, closely imbricate; scales ovate, mucronate, pubescent; bracts shorter than the panicle. - The largest species of bullrush, frequenting the muddy margins of rivers and ponds, U. S. to Arc. Am. July. (S. acutus Muhl)
6 S. pungens Vahl Culm nearly naked, 3-angled, corners acute and two of the sides concave, about 3f high and ending in a sharp point; lvs. few and short, from the top of the sheath; spikes lateral, 1 - 5, ovate, crowded and sessile, at. various distances below the point; glumes round-ovate, mucronate; bristles 6; style 2-cleft. - Ponds and marshes, fresh and salt, throughout N. America. (S. triqueter Mx.)
7 S. Olneyi Gray. Culm triquetrous-winged, leafless, 2 - 7f high; sheath radical, tipped with a short (1 - 2') leaf; spikes 6 - 12, sessile, aggregated, 2 - 3" long, placed 9 - 12" below the triangular apex of the stem; glumes roundish-ovate, mucronate; bristles 6 - 12: ach. obovate, plano-convex, gibbous at apex - Salt marshes, Sekonk river, R. I. (Olney), Tom river, N. Y., Kneiskern. Remarkably distinguished by its 3-winged stem. July.
8 S. Torreyi Olney. Culm 2f high, 3-angled, with concave sides, rather slender, leafy at the base; lvs. 2 or 3, If or more long, slender; spikes 2 - 4 (rarely 1), sessile, distinct, acute, ovate-oblong; scales ovate, mucronate, smooth; sty. 3-cleft; ach. obovate, acuminate, unequally 3-sided, shorter than the bristles. - Borders of ponds, N. Eng. to Mich. The stem here as in the last, is prolonged above the spikes, in the form of an involucral leaf. Jl., Aug. (S, mucronatus Ph. ? Torr.)