| 1 | Stigmas 3 and nut trigonous, or, when stigmas 2 and nut lenticular (plano-convex or biconvex) some or all of the spikelets peduncled or terminal spikelet ♂. Spikelets either dissimilar in appearance (the terminal one ♂ and some or all the lateral ones ♀), or similar in appearance (all bisexual). Base of the peduncles of the lateral spikelets or of the branches of the inflorescence surrounded by a utriculiform or ocreiform bracteole (cladoprophyllum); inflorescence sometimes reduced to a single terminal spikelet |
| 1' | Stigmas 2 and nut lenticular. Spikelets similar in appearance, bisexual, sessile. Cladoprophylla usually absent |
| 2 | Stigmas 3; nut trigonous. |
| 2' | Stigmas 2; nut lenticular (plano-convex or biconvex). |
| 3 | Inflorescence consisting of more than one spikelet. |
| 3' | Inflorescence consisting of a single terminal spikelet. |
| 4 | Lateral spikelets arising from a gaping, utriculiform, fertile (i.e. nut-bearing) cladoprophyll. Spikelets androgynous, up to 15 mm long. Bracts not sheathing. Stems 3-20 cm tall. Sp. 12 |
| 4' | Lateral spikelets arising from a sterile cladoprophyll, or sessile without cladoprophyll. |
| 5 | Stems scapiform, surrounded at the base by spadiceous sheaths in place of leaves. Leaves wide, conduplicate-petioled below. Secondary panicles contracted, very dense. Utricles with very long linear beak and very oblique mouth. Sp. 14 |
| 5' | Otherwise. |
| 6 | Spikelets peduncled, in fascicles in the axils of at least some of the sheathing bracts, all androgynous or some wholly ♂ or ♀. Utricles long-beaked. Spp. 17-20 |
| 6' | The peduncled or sessile spikelets or secondary panicles single or binate in the axils of the bracts. |
| 7 | Spikelets similar in appearance, androgynous (upper flowers ♂, lower ones ♀). |
| 7' | Spikelets dissimilar in appearance, unisexual (or rarely gynaecandrous), the terminal one or some upper ones ♂, the remainder ♀ (occasionally the ♀ spikelets may have a few ♂ flowers, and the ♂ spikelets a few ♀ flowers). Or most of the spikelets shortly cylindrical, the ♂ spikelets lateral, 1-5 just below some of the terminal ♀ spikelets. |
| 8 | Lower bracts not or only shortly (some millimeters) sheathing. |
| 8' | Lower bracts long sheathing. |
| 9 | Apex of nut truncate, 0.5-0.75 mm ø, hollowed out. Style centred in the apical hollow of the nut. Utricles lageniform or rhomboid-lageniform. Spp. 27-30. |
| 9' | Apex of nut not truncate. Style base pyramidally thickened, often broader than apex of nut. Spp. 35-38 |
| 10 | Flowering stems arising from the axils of the leaves which are crowded on a short stem and much longer than the flowering stems. Style flexuous. Nut with irregularly excavated sides, seated on a spongy, disk-like stipe. Sp. 26 |
| 10' | Flowering stems arising either from the centre of the leaves, or from lateral shoots bearing a few short-bladed leaves. |
| 11 | Spikelets small, up to 15(-20) mm long. |
| 11' | Spikelets longer. |
| 12 | Stems central. Spikelets numerous, ovoid or oblong-ovoid, arranged in often diffuse, compound panicles. Bracts long. Spp. 1-11 |
| 12' | Stems lateral. Spikelets few, globose-ovoid, in a simple panicle. Bracts shorter than 8 cm, the sheaths not included. Sp. 21 |
| 13 | Utricles densely many-nerved. Spikelets 1-8(-14). |
| 13' | Utricles distinctly but not densely nerved. Leaves with reddish sheaths splitting into fibres. Spikelets 6-numerous. Spp. 15-16 |
| 14 | Utricles ellipsoid, short-beaked, more or less ciliate on the margins, spongy-thickened at the base. Spikelets 1-3(-4). Spp. 35-38 |
| 14' | Utricles narrowly ellipsoid, long-beaked, more or less hispidulous on the faces, not spongy-thickened at the base. Spikelets 2-8(-14). Spp. 17-20. |
| 15 | Leaves not crowded in a basal rosette but inserted all over the stem, the upper ones merging into leafy bracts, the lower ones gradually decreasing in length and merging into bladeless sheaths. |
| 15' | Leaves crowded at the base of the stem, often also some higher on the stem. |
| 16 | Inflorescence a compound panicle consisting of 5-8 secondary panicles each containing numerous ♀ spikelets and 1-5 ♂ spikelets. Spikelets small, 4-8 mm long. Utricles glabrous, with short, ¼ mm long beak. Leaves sparsely hairy beneath., Sp. 13 |
| 16' | Inflorescence simple, racemose, consisting of 4-9 spikelets; terminal spikelet ♂ (sometimes a second, smaller one added), remaining spikelets ♀, 1.5-4 cm long. Utricles densely hispid, with distinct, c. 1 mm long beak. Leaves glabrous. Sp. 50 |
| 17 | Nut excavated in the middle, the apex abruptly narrowed into a conspicuous, hastiform, i.e. cylindric, 1/2-1/3 mm long beak expanding into the annulate apex. Spp. 22-25 |
| 17' | Nut without hastiform beak. |
| 18 | Apex of nut truncate, ¾-1 mm wide, hollowed out. Style centred in the apical hollow of the nut. Utricles lageniform or rhomboid-lageniform. Spp. 27-30 |
| 18' | Apex of nut not truncate, at most 0.5 mm wide. |
| 19 | Nut mitrate, i.e. contracted at the apex and then expanded into a discoid annulus. Utricles ovoid or ellipsoid. Spp. 31-34 |
| 19' | Nut not mitrate. |
| 20 | Utricles densely papillose, erostrate or but shortly beaked. Sp. 39 |
| 20' | Utricles not papillose, distinctly beaked. |
| 21 | ♀ Spikelets broadly ovoid or subglobose, with few narrowly lanceolate, c. 1 cm or more long utricles. Bracts sheathing. Rhizome short. Sp. 48. |
| 21' | ♀ Spikelets not broadly ovoid-subglobose. Utricles smaller. |
| 22 | Spikelets linear-cylindric, loosely flowered. Utricles nerveless (except for 2 submarginal nerves) or obscurely nerved, with long beak and oblique mouth. Bracts sheathing. |
| 22' | Spikelets oblong or cylindric. Utricles many-nerved. |
| 23 | Utricles hispidulous, brownish. Sp. 46 |
| 23' | Utricles glabrous, light green. Sp. 47 |
| 24 | Spikelets short-cylindric, few-flowered. Utricles fusiform-ellipsoid or rhomboid, at least towards the base many-nerved. Flowering stems lateral or central. Spp. 22-25 |
| 24' | Spikelets cylindric, densely many-flowered. |
| 25 | Utricles firm, of thick texture, short-beaked. Rhizome emitting strong stolons. Leaves conspicuously septate-nodulose. Spikelets erect. Bracts not or scarcely sheathing. Sp. 60 |
| 25' | Utricles membranous, with long beak (except in C. brownii subsp. brownii). |
| 26 | Spikelets erect. Utricles patulous, subinflated, many-nerved, with shortly bidentate beak. Style straight. Rhizome often creeping. Spp. 42-45. |
| 26' | Lower spikelets cernuous. Utricles widely patent to reflexed, closely many-ribbed, with bifurcate beak. Style flexuous. Rhizome cespitose. Sp. 49 |
| 27 | Utricles with whitish pubescent margins or hispidulous, densely and strongly many-nerved, 4-10 mm long. Spp. 35-38 |
| 27' | Utricles glabrous, 1.5-5 mm long. |
| 28 | Utricles rather large (4.5-5 mm long), with slender, linear, bidentate beak. Sp. 41 |
| 28' | Utricles small (1.5-4 mm long), with short, subentire or slightly emarginate beak. Sp. 40 |
| 29 | Bracts sheathing. Spikelets often in fascicles. Utricles often hispidulous, membranous, nerved, usually long-beaked. Stigmas often very long. Spp. 56-59 |
| 29' | Bracts not sheathing (or very shortly). |
| 30 | Lateral spikelets sessile or the lowest shortly peduncled, erect. Terminal spikelet Glumes muticous. Sp. 55 |
| 30' | Spikelets peduncled, cernuous. Glumes often awned. |
| 31 | Spikelets 3-8, single at the nodes, cylindric, short peduncled. Terminal spikelet ♂ or (often with exception of basal spikelets) spikelets gynaecandrous. Spp. 52-54. |
| 31' | Spikelets 6-50, single or binate at the nodes, the lower ones long-peduncled, all androgynous or some ♂, linear-cylindric. Sp. 51 |
| 32 | Spikelets androgynous (upper flowers ♂, lower ones ♀). |
| 32' | Spikelets gynaecandrous (upper flowers ♀, lower ones ♂) Utricles membranous. |
| 33 | Rhizome long-creeping. Spikelets 4-7. Utricles coriaceous, plano-convex, sharp-edged but not winged. Sp. 61 |
| 33' | Rhizome short, forming dense tufts. Spikelets numerous or very numerous. |
| 34 | Utricles coriaceous, with rounded margins. Bracts inconspicuous. Sp. 62 |
| 34' | Utricles membranous, with acute or winged margins. Lower bracts foliaceous. Sp. 63 |
| 35 | Utricles with rounded margins, densely whitish-puncticulate, beakless or very shortly beaked. Spikelets ebracteate (bracts glumiform). Sp. 66 |
| 35' | Utricles with acute or winged margins, not puncticulate. |
| 36 | Utricles obliquely erect, also when mature. Spikelets more or less distinctly bracteate. Sp. 65. |
| 36' | Utricles widely spreading or reflexed when mature. Spikelets not or inconspicuously bracteate (bracts glumiform). Sp. 64 |
