1Inflorescence consisting of a single (androgynous) spikelet terminating the stem. Stigmas 3; nut trigonous.
1'Inflorescence consisting of 2 or more spikelets.
2Utricles with whitish pubescent margins, or hispidulous, or winged and scabrid margined, 4-8 mm long. Glumes (many-)nerved. Style pyramidally thickened towards the base, persistent on the nut. Leaves (2-)3-10 mm wide.
2'Utricles glabrous, membranous and otherwise different, 2-5 mm long. Glumes 3-nerved in the centre, otherwise nerveless. Style not or but slightly thickened towards the base. Leaves ½-3 mm wide.
3Spikelets 2-8 cm long. Utricles with whitish pubescent margins.
3'Spikelets 6-12 mm. Utricles hispidulous or glabrous with scabrid margins.
4Utricles hispidulous in the upper ⅔, 4-6 mm, with conic-cylindric, 1-2.5 mm long beak.
4'Utricles glabrous with scabrid, distinctly winged margins, 6-8 mm, gradually narrowed into the 3 mm long beak
5Utricles (1.5-)2.5-3.5(-4) mm long, rather gradually tapering into a very short, subentire or slightly emarginate beak. Leaves ½-2 mm wide. Glumes 1.5-3 mm long.
5'Utricles 4.5-5 mm long, abruptly narrowed into a slender, linear, bidentate, c. 1½ mm long beak. Leaves 2-3 mm wide. Glumes 3-4 mm long
6Terminal and most of the other spikelets ♀, shortly cylindrical, the ♂ spikelets lateral, 1-5, just below some of the terminal ♀ spikelets. Inflorescence a compound panicle. Leaves all over the stem
6'Terminal spikelet bisexual or wholly ♂
7Terminal spikelet wholly male (exceptionally in some specimens with a few female flowers), or when spikelets in fascicles, 1-2 spikelets of the upper fascicle wholly male
7'Terminal spikelet always bisexual.
8Stigmas 3.
8'Stigmas 2.
9Leaves inserted all over the stem, the upper ones merging into leafy bracts, the lower ones gradually decreasing in length and merging into bladeless sheaths. Inflorescence simple, racemose, consisting of 4-9 spikelets. Spikelets 1.5-4 cm long. Utricles densely hispid, with distinct, c. 1 mm long beak. Leaves glabrous
9'Leaves basal and often also some higher on the stem.
10Nut excavated in the middle, the apex abruptly narrowed into a conspicuous, cylindric, 0.5-1.25 mm long beak expanding into the annular apex
10'Nut different.
11Apex of nut truncate, ¾-1 mm wide, hollowed out. Style centred in the apical hollow of the nut. Utricles lageniform or rhomboid-lageniform.
11'Apex of nut not truncate, at most 1/2 mm wide.
12Utricles 5-7 mm long. Apex of nut contracted into a cylindric, truncate, ⅔-1 mm long and wide neck.
12'Utricles 3½-4½ mm long. Apex of nut hardly or not contracted into a cylindric neck
13Leaves 5-10 mm wide. Beak of utricles 1.5-2 mm long. Stems arising from basal leaf axils
13'Leaves 1-3 mm wide. Beak of utricles ¾-1 mm long. Stems central
14Utricles densely papillose, subabruptly contracted into a very short, up to 1/2 mm long beak
14'Utricles not papillose, nut either mitrate or distinctly beaked.
15Nut mitrate, i.e. contracted at the apex and then expanded into a discoid annulus.
15'Nut not mitrate.
16Glumes of ♂ spikelets cup-shaped, the margins more than halfway connate in front. Stamens monadelphous (not always so in the lowermost flowers). Utricles many-nerved
16'Glumes of ♂ spikelets with free margins. Stamens free.
17Nut rhomboid with deeply concave faces.
17'Nut (long-)ellipsoid to ovoid or obovoid.
18Leaves 3-10 mm wide. Stems arising from basal leaf-axils. Utricles strongly many-nerved
18'Leaves 1-4(-6) mm wide. Stems central. Utricles nerveless to multinerved.
19Spikelets in fascicles of 3-20 from the axils of at least one of the bracts.
19'Spikelets solitary (exceptionally binate) from the axils of the bracts, or crowded at the apex of the stem.
20Utricles narrowly ellipsoid, 4-6.5 mm long, gradually tapering below into a stipe-like, ¾-1 mm long base, above into a 1-3 mm long beak
20'Utricles ovoid or ellipsoid, 2 1/3-3 1/2 mm long, scarcely stipitate; beak ¾-1 mm long.
21Utricles (8-) 12-13 mm, many-nerved. ♀ Spikelets broadly ovoid to subglobose, 15-25 mm long and wide, with few, divergent, narrowly lanceolate utricles. Bracts long-sheathing
21'Utricles at most 7.5 mm long. Other characters not so combined.
22Broader leaves 1-2 cm wide. Spikelets 5.5-16 cm long. Glumes vinaceous to dark red with a green, central stripe. Stoloniferous
22'Broader leaves at most 10 mm wide. Spikelets usually much shorter.
23Stems lateral. Lateral spikelets 6-12 by 4-7 mm, ♀ or androgynous. Utricles at least below many-nerved, 5-7 mm long. Glumes 2.5-4 mm. Nut 3-4 mm.
23'Stems central. Lateral spikelets more than 10 mm long, ♀ or rarely androgynous, when shorter than 12 mm nut 2.5-3 mm.
24Leaves 3-7 mm wide. Glumes 2.5-3½ mm, with a 1½-6 mm long awn. Lateral spikelets ♀
24'Leaves 1.5-3 mm wide. Glumes c. 4 mm long, muticous or mucronulate. Lateral spikelets androgynous
25Utricles 5-7.5 mm long; nut at least 2.25 mm long.
25'Utricles 3-5(-7) mm long; nut at most 2½ mm long, but mostly shorter; if the utricles are longer than 5 mm, the nut is at most 1⅔ mm long.
26Glumes 2-2.5 mm, with an antrorsely scabrous, 2-4 mm long awn. Utricles with deeply furcate 1.5-2 mm long beak, strongly and densely many-nerved, when ripe widely spreading or reflexed. Lower bracts much overtopping the inflorescence, scarcely sheathing
26'Glumes 3-6 mm long, whether or not awned.
27Utricles nerveless or obscurely few-nerved, except for the 2 marginal veins, 5-7.5 mm long. ♀ Spikelets linear-cylindric, lax-flowered, 2-9 cm by 3-7 mm. Glumes 3.5-6 mm, oblong to ovate, acute to very obtuse, translucent, with broad white margins and greenish midrib, the latter not reaching the apex, but sometimes excurrent into a short awn up to 1(-2) mm long
27'Utricles (strongly) many-nerved.
28Utricles 5.5-7.5 mm, fusiform. Glumes oblong-ovate, acute, very thin, dirty white with 3-nerved greenish central stripe, 3-5.5 mm long, muticous or mucronulate, rarely with a short awn
28'Utricles 5-5.5 mm. Glumes ovate, deeply emarginate at the top, pale with purplish margins, c. 3 mm long, the strong midrib excurrent into a firm, smooth or scabrid awn as long as the glume
29Utricles sparsely to rather densely hispidulous, nerveless except for 2 submarginal nerves, 3-4.5 mm long, with stout, 1-1.5 mm long beak. ♀ Spikelets linear-cylindric, 1.5-6 cm by 2.5-3.5 mm. Glumes 3-4.5 mm, with an hispidulous awn up to 1 mm long
29'Utricles glabrous, many-nerved or -ribbed.
30Utricles 4-5(-7) mm long, strongly many-nerved. Glumes 2-2.5 mm, with a 2-4 mm long awn. ♀ Spikelets 2.5-5 cm by 7-15 mm. Leaves 6-10 mm wide.
30'Utricles 3-4 mm (up to 6 mm in C. brownii subsp. transversa), strongly many-ribbed or plurinerved. Glumes 1.5-2.5 mm, excurrent into a ½-3.5 mm long awn. ♀ Spikelets 1.5-12 cm by 4-6 mm. Leaves 2-10 mm wide.
31Utricles strongly many-ribbed. ♀ Spikelets short-cylindric to cylindric, 1.5-3 cm by 5-6 mm. Glumes 1-2 mm with a 0.5-3.5 mm long awn. Nut 2.25-2½ mm. Leaves 3-4 mm wide
31'Utricles plurinerved. ♀ Spikelets (narrowly) cylindric, (1.5-)2.5-12 cm by 4-6 mm. Nut 1.5-2.25 mm. Leaves 2-10 mm wide.
32Plant densely cespitose, without stolons. Lower bracts long sheathing. Utricles olive-brown to fuscous. ♀ Spikelets 2½-12 cm long.
32'Plant stoloniferous. Bracts not sheathing. Utricles pale greenish to stramineous. ♀ Spikelets (1½-)2-5 cm
33Utricles densely covered with raised glandular papillae, slenderly nerved or nerveless. At least the lower spikelets subcernuous to pendulous. Lowest bract much overtopping the inflorescence.
33'Utricles not papillate, whether minutely punctulate or not.
34Glumes acute to obtusish, muticous or only the lower ones excurrent in a short, up to 1 mm long awn. Utricles slenderly nerved, 3-4 mm long
34'Glumes truncate or bilobed-emarginate, distinctly awned (awn l/2-2 mm long). Utricles mostly nerveless, 2¼-3½ mm
35Stems 3-40(-75) cm by 1-1½ mm. Utricles distinctly 8-14-nerved, 2-3.5 mm. Spikelets erect or suberect, terminal ♂, remainder ♀ or with a few ♂ flowers at the top, 1-6 cm. Leaves 1.5-4 mm wide
35'Stems 30-110 cm by up to 4 mm (below). Spikelets nodding, all lateral ones androgynous or 1(-2) at the base of the uppermost much smaller and wholly ♂, (3-)6-13 cm long. Leaves 3-12 mm wide
36Terminal spikelet (often all the spikelets) gynaecandrous (i.e. ♀ flowers above, ♂ ones below); ♂ flowers often so few that the spikelets have an entirely ♀ appearance.
36'Terminal spikelet and all or most of the other spikelets androgynous (i.e. ♂ flowers above, ♀ ones below).
37Stigmas 2. Nut lenticular (biconvex or planoconvex).
37'Stigmas 3. Nut trigonous.
38Spikelets all sessile, 0.5-1.5 cm long.
38'At least the lowest spikelet peduncled, cernuous, 3-6(-8) cm long
39Utricles distinctly winged on the margins. Lower bracts foliaceous, long, far exceeding the up to 15 cm long inflorescence
39'Utricles wingless. Bracts glumiform, the lowest exceptionally subulate to herbaceous, sometimes exceeding the 1.5-3.5(-6) cm long inflorescence.
40Utricles (3-)4-5(-5.5) mm long, when mature widely patent to reflexed, distinctly beaked, not whitish-punctulate
40'Utricles 2-2.5 mm long, suberect also when mature, scarcely beaked, densely whitish-punctulate
41Utricles hispidulous or sparsely pubescent. Nut mitrate (i.e. contracted at the apex and then expanded into a discoid annulus).
41'Utricles glabrous. Nut not mitrate.
42Utricles many-nerved. Glumes of ♂ flowers infundibuliform
42'Utricles obscurely nerved or nerveless. Glumes of ♂ flowers with free margins
43Lower bracts sheathing. Plants cespitose.
43'Bracts not sheathing. Plants stoloniferous
44Utricles broadly ellipsoid to subglobose, 3-4 mm long or ovoid-ellipsoid, 6 mm long
44'Utricles fusiform or fusiform-ellipsoid, 5-7.5 mm long.
45Utricles strongly many-nerved
45'Utricles nerveless except 2 marginal nerves or obscurely few-nerved.
46Stigmas 3.
46'Stigmas 2.
47Leaves pseudopetiolate, 1.5-3.5 cm wide, the base conduplicate. Stems central, erect, scapiform, the base surrounded by some brown, infundibuliform, up to 10 cm long leaf sheaths. Utricles very long beaked, the beak curved, bulbous at the base (to hold the thickened conical style-base), nearly linear towards the very oblique mouth, the whole beak 3-3.5 mm long, the utricle including the beak 6-7 mm long. Inflorescence paniculate with head-like very dense partial inflorescences
47'Leaves not pseudopetiolate (except in C. commixta). Other characters not so combined.
48Spikelets ped uncled, in fascicles from at least one of the sheathing bracts, sometimes compound.
48'Inflorescence racemose or spicate and spikelets peduncled or sessile, single or binate at the nodes or inflorescence a panicle and the secondary panicles single or binate at the nodes. Bracts sheathing or not.
49Utricles densely many-nerved, 5-9.5 by 1-2 1/3 mm. Spikelets 3-8 mm thick. Nut 3-4 mm long
49'Utricles nerveless or slenderly few-nerved, 3-6 by 0.6-1 mm. Spikelets 2-3.5 mm thick. Nut 1.5-3.5 mm long
50Flowering stems arising from the axils of the basal leaves, which are crowded on a short stem and much longer than the flowering stems. Inflorescence racemiform or paniculiform; spikelets 6-30, 8-30 mm long. Bracts usually shorter than the spikelets, with funnel-shaped sheaths and short blade. Nut irregularly rhomboid-ellipsoid or rhomboid-obovoid with faces excavated at base and apex; style flexuous
50'Flowering stems not arising from the axils of the basal leaves.
51Flowering stems developing from lateral shoots. Inflorescence a narrow, simple panicle, consisting of 6-12 head-like or racemose partial inflorescences each containing 1-8 spikelets 4-10 mm long. Utricles strongly many-nerved, 2.5-4 mm long.
51'Flowering stems central.
52Nut with a stout, cylindric, 1/2-3/4 mm wide neck. Style centred in the apical hollow of the nut.
52'Nut without stout cylindric neck. Style not centred in an apical hollow.
53Inflorescence spiciform, with 2-10 sessile spikelets. Utricles rhomboid-lageniform, 4.5-5 mm long
53'Inflorescence a slender compound panicle with numerous spikelets. Utricles ellipsoid-rhomboid, c. 4 mm long
54Lower bracts not or only very shortly sheathing.
54'Lower bracts long-sheathing.
55Inflorescence with 12 to numerous spikelets, spiciform, the lateral spikelets arising from a utriculiform, gibbous prophyll containing a ♀ flower or a nut. Stems 3-20(-30) cm tall
55'Inflorescence with 1-4 spikelets, or 1-4 heads, each consisting of 1-4 crowded sessile spikelets. The lateral spikelets not arising from a fertile prophyll.
56Utricles densely hispidulous in the upper ⅔. Glumes densely setulose. Lateral spikelets of the inflorescence sessile, ovoid or subglobose (sometimes absent)
56'Utricles at most scabrous at the margins towards the apex, the rest glabrous.
57Utricles 6-8 mm long, with a c. 3 mm long beak. Glumes 3-4.5 mm long, with a 1-1¾ mm long awn
57'Utricles 4-6.25 mm long, with a 1-2 mm long beak. Glumes 2.5-3 mm long, with a 1/2-1 mm long awn
58The longer spikelets at least 20 mm.
58'Spikelets never becoming longer than 20 mm.
59Spikelets many. Utricles 3-4.5 mm. Nut 2-3 mm.
59'Spikelets 1-many. Utricles 4-9.5 mm (if utricles less than 5 mm, spikelets few). Nut 3-4 mm.
60Beak of utricles straight. Utricles not inflated, ellipsoid or ellipsoid-obovoid, trigonous, pale to castaneous, slenderly nerved, sparsely to subdensely hispidulous, at least towards the apex. Leaves 2-10 mm broad
60'Beak of utricles curved. Utricles inflated, obscurely trigonous, ovoid to subglobose, strongly nerved, glabrous except the hispidulous margins towards the apex, at first yellowish green, ultimately red and more or less succulent. Leaves 5-18 mm broad
61Spikelets 2-many, branched (or when not branched the beak of the utricle 2-3 mm). Utricles 5-9.5 mm long, the beak 1.5-3 mm. Style-base slightly thickened
61'Spikelets not branched, 1-3(-4), 5-20 cm distant. Utricles 4-7 mm, the beak shorter. Style-base pyramidically thickened
62Leaves inserted all over the stem
62'Leaves (sub)basal, often 1-3 higher on the stem.
63Utricles densely pale to golden hispidulous, 5-6(-8) mm long. Spikelets at least 8 mm long
63'Utricles different, 2.25-6 mm long.
64Nut narrowly discoid-annulate at the apex. Utricles whitish setulose, not inflated. Secondary panicles mostly spiciform
64'Nut not narrowly discoid-annulate at the apex, or utricles glabrous, inflated.
65Leaves often pseudopetiolate, the broader leaves more than 15 mm wide. Spikelets ± patent, rather few-flowered, 5-10 mm long. Glumes ovate or oblong-ovate, obtuse or slightly emarginate, 2-3 mm long, the awn ½-2 mm. Utricles distinctly trigonous, ellipsoid, with prominent angles and flattish faces, membranous, c. 5- nerved on each face, 4-5(-6, extra-Mai.) by 1.5-1.75 mm, subabruptly beaked, the beak 1.5-2(-3, extra-Mai.) mm long, straight, bidentulate on the ventral side with very oblique mouth
65'Leaves not pseudopetiolate, rarely more than 15 mm wide.
66Utricles glabrous, whether inflated or not, shiny and conspicuously 2-4-nerved on each face and then glumes muticous or mucronulate, or dull, 3-5-spongy-ribbed or strongly 5-10-nerved on each face, with oblique, often scabrid beak.
66'Utricles glabrous, or hairy, not inflated, obscurely to conspicuously nerved or spongy-ribbed, the beak bidentate or bidentulate.
67Utricles shiny, triquetrous, not inflated, conspicuously few-(c. 2-4-)nerved on each face, olivaceous to reddish-castaneous, 2.25-5 by ½-1 mm, with slender, subulate or scarcely tapering beak which is about as long as the body or slightly longer (1-2.5 mm long). Glumes 1.5-2.5(-4.5) mm, about as long as the body of the utricle, muticous or rarely mucronulate
67'Utricles rather dull, inflated or subinflated, or at least not triquetrous, strongly spongy 3-5-ribbed on each face or strongly 5-10-nerved. (If different proceed under 66 second lead.)
68Utricles spongy 3-5-ribbed on each face, stramineous or brown, 2-4 by 1(-1.5) mm, abruptly beaked, the beak usually straight, with oblique mouth often becoming bifid, ¾-1.5 mm long
68'Utricles strongly many-nerved (5-7 or c. 10 nerves on each face), 3½-5 by 1-2 1/3 mm.
69Utricles distinctly inflated, obscurely trigonous, c. 10 nerves on each face. The rather compact ♂ part of the spikelets as long as to usually much longer than the ♀ part, rarely shorter. Glumes 2-3.5 mm, with an awn to 3.5 mm. Nut often rostrate
69'Utricles rhomboid, trigonous, 5-7 nerves on each face. Nut erostrate.
70The (often plumose) ♂ part of the spikelets shorter than to about as long as the ♀ part. Glumes 1.5-2 mm, with an awn of 1-3 mm.
70'The ♂ part longer than the ♀ part of the spikelets. Glumes 2-2¾ mm, with an awn of ¾-2 mm
71Glumes distinctly awned, broadly ovate. At least in the lowest glumes of a large part of the spikelets the awn longer than the glume. Utricles with (3-)4-6 strong nerves on each face, glabrous and smooth (glossy), or hispidulous on the margins in the upper part, light green to stramineous, (2½-)3-4 by 1-1.25 mm, the beak compressed, shorter to about as long as the body of the utricle, 1-1.5 mm long. (If the utricles are hispidulous, see 3. C. cruciata.).
71'Glumes whether awned or not, awn never longer than glume.
72Glumes muticous or mucronulate, rarely awned. Utricles obscurely nerved, only 2 nerves more prominent, glabrous at the base, otherwise densely scabrid- pubescent, blackish fuscous or greenish, 2¾-4.5 by c. 1 mm; the beak straight, compressed, deeply bidentate, but often originally oblique, blackish fuscous, the mouth with whitish hyaline margins
72'Glumes often awned. Beak of utricles not blackish fuscous, or utricles not scabrid-pubescent except at the base, or characters otherwise combined.
73Glumes ovate or broadly ovate, acutish or obtuse. Utricles obtusely trigonous, strongly spongy 3-5-ribbed on each face, glabrous, except sometimes on the margins
73'Glumes ovate or narrowly ovate, acute. Utricles distinctly trigonous or triquetrous, more or less distinctly several-nerved to obscurely nerved, glabrous or hairy.
74The ♂ and ♀ part of the spikelets of same length. Glumes 1.5-2.5 mm
74'In the longer spikelets the ♂ part much longer than the few-flowered ♀ part. Glumes 2.5-4.5 mm
75Rhizome long-creeping, slender. Leaves canaliculate or convolute, c. 1 mm wide. Spikelets approximate, forming an oblong, 1-1.5 cm long head. Utricles nerveless, glabrous
75'Rhizome short, plant forming dense tufts. Leaves usually wider than 1 mm.
76Spikelets very numerous, forming a slender, 5-25 cm long, oblong-cylindric, contracted, spikelike 1-2 cm broad panicle. Leaves with very scabrous margins, 3-10 mm wide. Utricles coriaceous
76'Spikelets 4-10(-25), forming a head-like or spike-like 1-3(-5) cm long inflorescence, or spikelets up to 50, in a lax raceme or in (2-)4-8 fascicles of 2-7 spikelets each and inflorescence up to 50 cm. Utricles membranous.
77Spikelets all sessile. Cladoprophylls (see below) absent. Utricles ovate or ovate-lanceolate, not cordate at the base, winged on the margin, 3½-4.5 mm long. Glumes mucronate
77'At least the lower spikelets distinctly peduncled. Peduncles of the lateral spikelets at the base surrounded by an ocreiform or utriculiform bracteole (cladoprophyllum) which is often hidden in the sheath of the bract subtending the spikelet.
78Bracts not sheathing. Spikelets linear-cylindric, very densely flowered, (2-)6-13 cm long.
78'Bracts sheathing. Spikelets loosely or somewhat densely flowered, up to 4.5 cm long.
79Utricles densely beset with ferrugineous papillae
79'Utricles epapillate
80Inflorescence very lax, only 1 spikelet at each node. Glumes with a stoutish, up to 5 mm long awn. Utricles glabrous except for the sparsely hispid beak (rarely the margin setulose)
80'Spikelets often in fascicles at the nodes. Glumes muticous or minutely apiculate (rarely an awn up to 2 mm present). Utricles setulose at least on the margins.
81Lower bract setaceous, suddenly widening into a spathaceous, reddish brown base clasping the base of the spikelets. Glumes 4-6 mm
81'Lower bracts foliaceous.
82Glumes distinctly shorter than to about as long as the utricle, 2-4 mm, rarely some of them to 5 mm. Stigmas shorter than to about as long as the utricles, up to c. 5 mm
82'Glumes about as long as the utricles, 3.5-5 mm. Stigmas very long (7-12 mm), always much longer than the utricles