[++][++] _Perennial, propagating by corm-like tubers from the base; spikelets narrow, ac.u.minate, often teretish; scales oblong-lanceolate; achene linear-oblong._

18. C. strigsus, L. Culm mostly stout (1--3 high); most of the rays of the umbel elongated (1--5'), their sheaths 2-bristled; _spikelets 5--25-flowered_, spreading; scales several-nerved, much longer than the achene.--Damp or fertile soil, Canada to Fla., west to Minn., Tex., and the Pacific. Very variable in the number and length of the rays of the simple or compound umbel, and in the size of the spikelets (2--6 or even 12" long), more or less densely crowded on the axis.

-- 4. DICLiDIUM. _Style 3-cleft; spikelets narrow, terete or nearly so, few--many-flowered, the scales closely appressed and the broad wings of the jointed rhachis enclosing the triangular achene._

19. C. specisus, Vahl. Culm stout, _mostly low_ (5--20' high); _rays of the simple or compound umbel mostly all short and crowded; spikelets 10--20-flowered, yellowish-brown_ at maturity (3--7" long), the short joints of its axis winged with very broad scaly margins which embrace the _ovate triangular achene; the scales ovate, obtusish, imbricately overlapping_. (C. Michauxia.n.u.s, _Gray_, Manual; not _Schultes_.)--Low grounds and sandy banks, N. Eng. to Fla., west to Minn. and Tex.

20. C. Engelmanni, Steud. Resembles n. 19; but the _spikelets more slender_ and terete, _somewhat remotely 5--15-flowered_, the zigzag joints of the axis slender and narrowly winged, and the oblong or oval broadly scarious _scales proportionally shorter_, so as to expose a part of the axis of each joint, _the successive scales not reaching the base of the one above_ on the same side; achene oblong-linear, very small.--Low grounds, Ma.s.s. to Wisc. and southward.

-- 5. MARiSCUS. _Spikelets 1--4-flowered, subterete, usually in dense heads; scales oppressed, several-nerved, the lower empty and often persistent after the fall of the rest of the spikelet; joints of the rhachis winged, enclosing the triangular achene. Perennial._

[*] _Spikelets slender and ac.u.minate, more or less refracted in usually close umbelled spikes.--Connecting with -- 4._

21. C. Lancastriensis, Porter. Culm (1--2 high) triangular; _leaves rather broadly linear_; umbel of 6--9 mostly elongated rays; _spikelets very numerous in short-oblong close heads_, soon reflexed, of 3--6 narrow scales, the upper and lower empty, twice the length of the linear-oblong achene, which is nearly 1" long.--Rich soil, Penn. and N. J. to Ala.

22. C. retrofractus, Torr. Culm and leaves usually minutely downy and rough on the obtusish angles (1--3 high); umbel many-rayed; _spikelets slender-awl-shaped_, very numerous in obovate or oblong heads terminating the elongated rays, _soon strongly reflexed, 1--2-flowered_ in the middle (3--5" long); scales usually 4 or 5, the two lowest ovate and empty, the fertile lanceolate and pointed, the uppermost involute-awl-shaped; achene linear, 1" long.--Sandy fields, N. J. to Fla. and Tex.

23. C. refractus, Engelm. Culm 1--2 high; rays usually more or less elongated; spikelets very slender, in rather loose heads, divaricate or more or less reflexed, 2--4-flowered; achene linear, 1" long.--N. J.

to N. C. and Mo.

[*][*] _Spikelets very short, blunt, in densely compacted globose or cylindrical heads._

24. C. ovularis, Torr. Culm sharply triangular (6'--2 high); umbel 1--6-rayed; _spikelets_ (50--100) in a _globular head, 3-flowered, oblong, blunt_ (1--2" long); scales ovate, obtuse, a little longer than the ovate-oblong achene.--Sandy dry soil, southern N. Y. to Fla., west to Ill., Ark., and Tex.--Var. ROBuSTUS, Boeckl., is a form with large heads (4--8" long), the spikelets 3--4-flowered. (C. Wolfii, _Wood_.)--Ill. to Ark., and southward.

25. C. Torreyi, Britton. Like the last, but the _heads cylindrical or oblong, spikelets usually 2-flowered_, and _achene linear-oblong_.--L.

Island to Fla., west to Tex.

2. KYLLiNGA, Rottboell. (Pl. 1.)

Spikelets of 3 or 4 two-ranked scales, 1--1-flowered; the 2 lower scales minute and empty, as in Cyperus, -- 4, but style oftener 2-cleft and achene lenticular; spikes densely aggregated in solitary or triple sessile heads.--Culms leafy at base; involucre 3-leaved. (Named after _Peter Kylling_, a Danish botanist of the 17th century.)

1. K. pumila, Michx. Annual; culms 2--9' high; head globular or 3-lobed, whitish-green (about 4" broad), spikelets strictly 1-flowered; upper scales ovate, pointed, rough on the keel; stamens and styles 2; leaves linear.--Low grounds, Ohio to Ill., south to Fla. and Tex. Aug.

3. DULiCHIUM, Pers. (Pl. 1.)

Spikelets many- (6--10-) flowered, linear, flattened, sessile in 2 ranks on axillary solitary peduncles emerging from the sheaths of the leaves; scales 2-ranked, lanceolate, decurrent, forming flat wing-like margins on the joint below. Perianth of 6--9 downwardly barbed bristles.

Stamens 3. Style 2-cleft above. Achene flattened, linear-oblong, beaked with the long persistent style.--A perennial herb, with a terete simple hollow culm (1--2 high), jointed and leafy to the summit; leaves short and flat, linear, 3-ranked. (An alteration of _Dulcichinum_, an old name for a species of Cyperus.)

1. D. spathaceum, Pers.--Borders of ponds, N. Scotia to Fla., west to Minn. and Tex. July--Sept.

4. ELEoCHARIS, R. Br. SPIKE-RUSH. (Pl. 3.)

Spikelet single, terminating the naked culm, many--several-flowered.

Scales imbricated all round in many (rarely in 2 or 3) ranks. Perianth of 3--12 (commonly 6) bristles, usually rough or barbed downward, rarely obsolete. Stamens 2--3. Style 2--3-cleft, its bulbous base persistent as a tubercle jointed upon the apex of the lenticular or triangular achene.--Leafless, chiefly perennial, with tufted culms sheathed at the base, from matted or creeping root-stocks; flowering in summer. (Name from ????, _a marsh_, and ?a??? _to delight in_; being marsh plants.)

-- 1. _Spikelet terete, hardly if at all thicker than the spongy-cellular culm; scales firmly persistent; style mostly 3-cleft; bristles 6 (rarely 7), firm or rigid, mostly barbed downward, equalling or surpa.s.sing the triangular or lenticular achene._

[*] _Spikelet linear or lanceolate-awl-shaped, few-flowered; scales (only 3--9) few-ranked, convolute-clasping the long flattened joints of the axis, lanceolate, herbaceous (green) and several-nerved on the back, and with thin scarious margins._

1. E. Robbinsii, Oakes. _Flower-bearing culms exactly triangular_, rather stout, erect (8'--2 high), also producing tufts of capillary abortive stems or fine leaves, which float in the water; sheath obliquely truncate; spikelet 4--10" long; achene oblong-obovate, triangular, minutely reticulated, about half the length of the bristles, tipped with a flattened awl-shaped tubercle.--Shallow water, N. Eng. to Fla.

[*][*] _Spikelet cylindrical, many-flowered, 1--2' long; scales in several ranks, firm-coriaceous with scarious margin, pale, nerveless or faintly striate; culms large and stout (2--4 high); basal sheaths often leaf-bearing._

2. E. equisetodes, Torr. _Culm terete, knotted as if jointed by many cross-part.i.tions; achene smooth_ (the minute reticulation transversely linear-rectangular), with a conical-beaked tubercle.--Shallow water, R. I. to Fla., west to Mich. and Tex.

3. E. quadrangulata, R. Br. (Pl. 3, fig. 6--9.) _Culm continuous and sharply 4-angled; achene finely reticulated_, with a conical flattened distinct tubercle.--Shallow water, central N. Y. to Mich., and southward; rare.

-- 2. _Spikelet terete and turgid-ovate, much thicker than the very slender culm; scales thin-coriaceous or firm-membranaceous, persistent, ovate; style 3-cleft; bristles stout, barbed downward (or sometimes upward), as long as the striate and pitted-reticulated triangular achene and its tubercle; culms tufted from fibrous roots, 1--2 high._

4. E. tuberculsa, R. Br. (Pl. 3, fig. 10.) _Culms flattish_, striate; spikelet 3--6" long, many-flowered; _tubercle flattish-cap-shaped, as large as the body of the achene_.--Wet sandy soil, from Ma.s.s. along the coast to Fla.

5. E. tortilis, Schult. _Culms sharply triangular, capillary_, twisting when dry; spikelet 2--3" long, few-flowered; _conical-beaked tubercle much smaller than the achene_. (E. simplex, _Torr._)--Eastern sh.o.r.e of Md. to Fla.

-- 3. _Spikelets terete, much thicker than the culm, many-flowered; scales imbricated in many or more than 3 ranks, thin-membranaceous or scarious, with a thicker midrib, usually brownish or purplish, sometimes deciduous._

[*] _Style 2-cleft (often 3-cleft in n. 7 and 10) and the smooth achene lenticular; culms slender or thread-form, terete or compressed._

[+] _Annuals; culms tufted, from fibrous roots._

6. E. capitata, R. Br. Culms terete, --8' high or more; _spikelets ovate to oblong_ (1--3" long), obtuse, 15--40-flowered; _scales thickish_, round-ovate, _obtuse_, brown or brownish with green keel and paler margins; stamens 2; achene obovate, _black, about equalling the 6--8 bristles_, tipped with a flattened or saucer-shaped tubercle. (E.

dispar, _E. J. Hill_.)--In sand or gravel near sloughs, Md. (_Canby_) to Fla. and Tex.; N. Ind. (_Hill_). (S. Am., etc.)

7. E. ovata, R. Br. Culms nearly terete, 8--14' high; _spikelet globose-ovoid to ovate-oblong, obtuse_, 1--6" long (dull brown); _scales very obtuse, densely crowded in many ranks; style_ 3- (rarely 2-) _cleft_; achene obovate with narrow base, pale-brownish, shining, shorter than the 6--8 bristles, _broader than the short-deltoid, acute and flattened tubercle_. (E. obtusa, _Schult._)--Muddy places, N. Brunswick to Minn., south and westward. Variable as to the length of its bristles. A low form, with smaller and more narrowly obovate achenes, and the bristles very short or none, is E. diandra, _Wright_. A dwarf form occurs with very small and few-flowered heads. (Eu.)

8. E. Engelmanni, Steud. Like the last; spikelets usually narrowly cylindrical and acute or acutish, 2--8" long; achene broad and truncate, the tubercle covering the summit; bristles not exceeding the achene. (E. obtusa, var. detonsa, _Gray_.)--Ma.s.s. to Penn. and Mo.

[+][+] _Perennials, with running rootstocks._

9. E. olivacea, Torr. (Pl. 2, fig. 1--5.) Culms flattish, grooved, diffusely tufted on slender matted rootstocks (2--4' high); _spikelet ovate, acutish, 20--30-flowered; scales ovate, obtuse_, rather loosely imbricated (purple with a green midrib and slightly scarious margins); achene obovate, dull, abruptly beaked with a narrow tubercle, shorter than the _6--8 bristles_.--Wet, sandy soil, Ma.s.s. to N. C., and western N. Y.

10. E. palsutris, R. Br. Culms nearly terete, striate, 1--5 high; _spikelet oblong-lanceolate, pointed, many-flowered; scales ovate-oblong_, loosely imbricated, reddish-brown with a broad and translucent whitish margin and a greenish keel, the upper acutish, the lowest rounded and often enlarged; achene rather narrowly obovate, somewhat shining, crowned with a short ovate or ovate-triangular flattened tubercle, shorter than the _usually 4 bristles_.--Very common, either in water, when it is pretty stout and tall, or in wet gra.s.sy grounds, when it is slender and lower. (Eu., Asia.)--Var. GLAUCeSCENS, Gray. Culms slender or filiform; tubercle narrower, acute, beak-like, sometimes half as long as the achene. With the type.--Var. CaLVA, Gray.

Bristles none; tubercle short, but narrower than in the type.--Var.

VGENS, L. H. Bailey. Culms very stout, rigid; achene more broadly obovoid. Lake Champlain and along the Great Lakes to Minn.

[*][*] _Achene triangular or turgid; style 3-cleft._

[+] _Bristles at least equalling the smooth achene, downwardly barbed, persistent._

11. E. rostellata, Torr. _Culms flattened and striate-grooved_, wiry, erect (1--2 high), _the sterile ones reclining, rooting and proliferous_ from the apex (1--2 high), the sheath transversely truncate; _spikelet spindle-shaped_, 12--20-flowered; scales ovate, obtuse (light-brown); achene obovate-triangular, narrowed into the confluent pyramidal tubercle, which is overtopped by the 4--6 bristles.--Marshes, N. Eng. to S. C., west to Mich. and Ky.

12. E. intermedia, Schultes. _Culms capillary, wiry_, striate-grooved, densely tufted from fibrous roots, _diffusely spreading or reclining_ (6--12' long); _spikelet oblong-ovate, acutish, loosely 10--20-flowered_ (2--3" long); scales oblong, obtuse, green-keeled, the sides purplish-brown; achene obovoid with a narrowed base, beaked with a slender conical-awl-shaped distinct tubercle, which nearly equals the 6 bristles.--Wet slopes, Penn. to Iowa, north to Canada.

13. E. Torreyana, Boeckl. Like the preceding, but more capillary and heads smaller (1--2" long), _sometimes proliferous_, the one or more short new culms from the axil of its lowest scale, which persists as an herbaceous bract; achene very much smaller, with sharper angles and a short conical tubercle, which is hardly equalled by the 3--6 slender bristles. (E. microcarpa, var. filiculmis, _Torr._)--Wet pine-barrens, N. J. to Fla.

(Addendum) 13^a. E. albida, Torr. Like n. 12 and 13 in habit, somewhat stouter; spikelet dense, ellipsoidal or oblong, 1--4" long, acutish, with pale obtuse scales; achene very small, triangular-obovate, very smooth, with a broadly triangular tubercle upon a narrow base, shorter than or exceeding the reddish bristles.--Salt marshes, Northampton Co., Va. (_Canby_), and south to Fla. and Tex.