1 "Spikelets with several–many flowers producing nuts, usually only 1 or 2 lowest glumes empty." 2 1 "Spikelets or pseudospikelets with 1 or 2 flowers producing nuts, usually several–many empty glumes at the base of the spikelet or pseudospikelet." 17 2 "Stems noded and leafy (also occasionally noded in aquatic species such as Isolepis fluitans, but then not large perennials, and bristles absent); hypogynous bristles or scales present." 3 2 "Culms not noded; leaves all basal; hypogynous bristles or scales present or absent." 5 3 "Three hypogynous scales inflated and more or less petaloid; 3 hair-like bristles also present; glumes with a long mucro about as long as glume." Fuirena 3 "All hypogynous bristles hair-like; glumes with a mucro no more than half glume length." 4 4 "Spikelets less than 1 cm long; inflorescence branches scabrous; hypogynous bristles much longer than nut." Scirpus 4 "Spikelets 1–2.5 cm long; inflorescence branches not scabrous; hypogynous bristles shorter than or equalling nut." Bolboschoenus 5 "Style base enlarged and persistent on nut." 6 5 "Style base enlarged or not, but not persistent on nut." 7 6 "Inflorescence not subtended by leafy bracts; leaves reduced to sheaths, glabrous; hypogynous bristles usually present." Eleocharis 6 "Inflorescence subtended by leafy bracts; leaves with well-developed blade, hairy near mouth of sheath; hypogynous bristles always absent." Bulbostylis 7 "Hypogynous bristles present." Schoenoplectus 7 "Hypogynous bristles absent." 8 8 "Style base enlarged but not persistent." 9 8 "Style base not enlarged or persistent." 10 9 "Glumes spirally arranged and spikelets terete, or rarely distichous and spikelets compressed (but then inflorescence with numerous spikelets)." Fimbristylis 9 "Glumes distichous or upper part of spikelet twisted so as to be more or less spiral; spikelets compressed; inflorescence of 1–6 spikelets." Abildgaardia 10 "Style 2-fid." 11 10 "Style 3-fid." 13 11 "Glumes distichously arranged in spikelet. (Subgenus 4 Pycreus)." Cyperus 11 "Glumes spirally arranged in spikelet." 12 12 "Involucral bracts glume-like or leaf-like, from shorter than inflorescence to twice as long as it (to 1.5 cm long); spikelets 2–8 mm long." Isolepis 12 "Involucral bracts culm-like, usually at least 4 times as long as inflorescence (to 25 cm long); spikelets 5–15 mm long." Schoenoplectus 13 "Rachilla internodes thickened and clasping nut at maturity. (Subgenus 3 Torulinium)." Cyperus 13 "Rachilla neither thickened nor clasping nut." 14 14 "Glumes distichously arranged in spikelet (spiral in Cyperus hamulosus but then plant has smell of fenugreek). (Subgenus 1 Anosporum, Subgenus 2 Cyperus)." Cyperus 14 "Glumes spirally arranged in spikelet, not smelling of fenugreek." 15 15 "Nuts transversely wrinkled and/or stout perennials." Schoenoplectus 15 "Nuts variously marked but never transversely wrinkled; small annuals or perennials." 16 16 "Perennial with long-creeping, thick, woody rhizome to 1 cm diam.; minute hypogynous disc under nut ." Ficinia 16 "Plants in small tufts or with filiform rhizome; no disc under nut." Isolepis 17 "Female flowers enclosed in sac-like utricle." 18 17 "Flowers not enclosed in a utricle." 19 18 "Slender rachilla inside utricle with a stiff exserted hooked tip; inflorescence always a single spike." Uncinia 18 "No slender hooked rachilla inside the utricle; inflorescence of (1–) several–many spikes." Carex 19 "Female flowers apparently terminal, always only 1 per pseudospikelet (floral unit)." 20 19 "Female or bisexual flowers lateral and axillary, one to many in a spikelet." 22 20 "Leaves flat, leafy, usually present along the culms as well as at the base; involucral bracts flat, leafy; nut much longer than glumes." Exocarya 20 "Leaves terete or reduced to sheaths, at base of culm only; involucral bracts terete but often broad and flattened at the base; nut shorter than to equalling glumes." 21 21 "Nut biconvex; style 2-fid; inflorescence spike-like; nut finely striate longitudinally but not ribbed." Lepironia 21 "Nut terete to obtusely trigonous, obovoid to globose; style (2- to) 3- or 4-fid; inflorescence globose, hemispherical, or ovoid; nut strongly ribbed longitudinally." Chorizandra 22 "A hypogynous disk or 1 or 2 hyaline scales or 2–6 hypogynous bristles or scales present at base of nut (not always falling with nut)." 23 22 "Hypogynous bristles, scales and disk absent." 36 23 "Nut more or less enclosed in 2, or occasionally 1, hyaline scales." Lipocarpha 23 "Nut without hyaline scales." 24 24 "Style simple or 2-fid." 25 24 "Style 3–8-fid." 26 25 "Style base differentiated, enlarged, and persistent; leaves without a ligule." Rhynchospora 25 "Style base not differentiated or enlarged or persistent; leaves with a membranous ligule." Cyathochaeta 26 "Hypogynous disk present at base of nut." 27 26 "Hypogynous bristles or scales present at base of nut." 28 27 "Glumes spirally arranged; most flowers bisexual; nut brownish, tough." Cladium 27 "Glumes distichous; flowers unisexual; nut with white to purplish, fragile pericarp." Scleria 28 "Upper internodes of rachilla prominently zigzag." Schoenus 28 "Upper internodes straight." 29 29 "Style base persistent, often enlarged in fruit." 30 29 "Style base deciduous." 34 30 "Inflorescence head-like." 31 30 "Inflorescence panicle-like, umbel-like, or spike-like." 32 31 "Ligule membranous, glabrous; inflorescence obconical or fan-shaped; leaf sheaths glabrous." Ptilothrix 31 "Ligule membranous and ciliate; inflorescence globose; leaf sheaths long-ciliate on upper margins." Gymnoschoenus 32 "Bristles 6, as long as, or longer than, the nut." Carpha 32 "Bristles 2 to 5, much shorter than the nut." 33 33 "Robust perennials with inflorescence c. 40 cm long. (Gahnia erythrocarpa)." Gahnia 33 "Slender perennials with inflorescences 1–4[–30] cm long." Tetraria 34 "Glumes spirally arranged in the spikelet; hypogynous scales inflated." Lepidosperma 34 "Glumes more or less distichously arranged in the spikelet; hypogynous scales flat, not thickened." 35 35 "Hypogynous scales falling with the nut; leaf without pseudopetiole." Tricostularia 35 "Hypogynous scales persistent on rachilla after nut falls; leaf with pseudopetiole." Oreobolus 36 "Style simple or 2-fid." 37 36 "Style 3–8-fid." 40 37 "Style base enlarged, persistent; ligule absent." Rhynchospora 37 "Style base enlarged or not, but not persistent." 38 38 "Inflorescence umbel-like; ciliate ligule present." Trachystylis 38 "Inflorescence of 1 to 3 dense, clustered heads; ligule absent." 39 39 "Hyaline scales usually 2 enclosing nut, occasionally 1 or absent; apparent glumes (= spikelet bracts) flat with 0–2 nerves on each side of midrib; nut dorsiventrally compressed, trigonous or plano-convex." Lipocarpha 39 "Hyaline scales absent; glumes keeled, with 2–5 nerves on each side of midrib; nut laterally compressed (i.e. with an edge next to rachilla), biconvex. (Subgenus 5 Kyllinga)." Cyperus 40 "Upper internodes of rachilla zigzag." Schoenus 40 "Upper internodes of rachilla straight." 41 41 "Annual; inflorescence of 1 to 3 clustered heads with numerous spikelets." Lipocarpha 41 "Perennials; inflorescence panicle-like, spike-like, or occasionally reduced to a few clustered spikelets." 42 42 "Leaves reduced to blade no more than 1 cm long." 43 42 "Leaves with well-developed blade to 1 m long." 45 43 "Persistent style base not separated from body of nut by a constriction." Baumea 43 "Persistent style base separated from body of nut by a constriction." 44 44 "Leaves without a ligule." Caustis 44 "Leaves with a ligule. (Tetraria capillaris)." Tetraria 45 "Leaves 2-ranked, isobilateral." Baumea 45 "Leaves 3-ranked, dorsiventral." 46 46 "Nut borne on inconspicuous hypogynous disk (disk may stay on rachilla rather than fall with nut)." Cladium 46 "Nut not borne on a hypogynous disk." 47 47 "Spikelets disarticulating as a unit from axis at maturity. (Subgenus 2 Cyperus)." Cyperus 47 "Spikelets persistent, nuts falling separately from glumes at maturity." 48 48 "Leaves with a ligule." Gahnia 48 "Leaves without a ligule" Tetraria