Inflorescence simple or compound, umbel-like or head-like, rarely reduced to one spikelet; involucral bracts mostly leaf-like. Spikelets many- or few-flowered, flattened or terete, spicate or digitate at the ends of the ultimate branches or sometimes occupying the whole of the ultimate branches. Rachilla straight or flexuous, often bordered by hyaline or coloured membranous wings. Glumes distichous (very rarely spiral), concave or keeled, keel usually green, all except the lowest 2 or 1 subequal and containing bisexual flowers or the terminal one sometimes male. Hypogynous bristles absent. Stamens 1–3. Style 2- or 3-fid, continuous with ovary, not thickened at base, deciduous.
Nut trigonous or lenticular, glabrous, smooth or punctulate, rarely coarsely reticulate or transversely elongated.
This genus is taken here in the broad sense to include species sometimes assigned to segregate genera such as Kyllinga and Pycreus. The tribe Cypereae is undergoing further study to assess whether segregate genera (including Lipocarpha) should be accepted.
| | Key to the species | |
| 1 | Style 3-fid; nut 3-angled in cross-section (more or less trigonous) | 2 |
| Style 2-fid; nut lenticular, biconvex, plano- or concavo-convex | 106 |
| 2 | Dwarf annuals smelling of fenugreek (at least when dried) | 3 |
| Annuals or perennials but not smelling of fenugreek
Back to 1 | 4 |
| 3 | Spikelets flattened, with glumes arranged distichously; nut a third to half as long as glume | Cyperus squarrosus |
| Spikelets more or less angular, with glumes arranged spirally; nut about two-thirds as long as glume
Back to 2 | Cyperus hamulosus |
| 4 | Spikelets with 4 or more flowers, flattened and with glumes overlapping at least a quarter the length of the glume immediately above on the same side of the rachilla and often spreading widely (at least at maturity) | 5 |
| Spikelets 1–3-flowered, or up to 16-flowered but then terete and with glumes remote (i.e. with glumes not or scarcely overlapping the glume immediately above on the same side of the rachilla) and closely appressed to rachilla
Back to 2 | 95 |
| 5 | Spikelets arranged spicately on the rachis of the ultimate branches of the inflorescence, in very short to elongated spikes | 6 |
| Spikelets digitately or subdigitately clustered, in clusters sometimes dense on a much reduced rachis, sometimes very few in number or solitary and then often appearing lateral when the lowest bract is erect
Back to 4 | 36 |
| 6 | Culms 2–5 m high; inflorescence with 100–250 primary branches of similar length | Cyperus papyrus |
| Culms less than 2 m high; inflorescence with fewer than 15 primary branches, usually of varying length
Back to 5 | 7 |
| 7 | Rachilla of the spikelet distinctly winged, the wings sometimes falling later | 8 |
| Rachilla not winged or with very narrow wings
Back to 6 | 26 |
| 8 | Involucral bracts (and associated branches) distinctly separated on axis from neighbouring bracts by up to 3 mm; perennial producing numerous globose, bulb-like tubers with deciduous stiff, smooth, shining, blackish coats | Cyperus bulbosus |
| Involucral bracts and branches inserted very closely together; perennials, rarely producing tubers (and these grey-brown, oblong or ellipsoid or globose, with more or less persistent fibrous, dull, yellow-brown to grey-brown coats)
Back to 7 | 9 |
| 9 | Spikelets fewer than 20 per spike | 10 |
| Spikelets usually more than 20 per spike, numerous to very numerous
Back to 8 | 20 |
| 10 | Spikelets more than 1.5 mm wide in side view, more or less flattened; plants often with tuber-bearing rhizomes | 11 |
| Spikelets 1–1.5 mm width/diam., flattened to terete; rhizome, if present, not tuber-bearing
Back to 9 | 19 |
| 11 | Perennials with short rhizome, not tuber-bearing; glumes pale red-brown with broad white or yellowish margins or yellow-brown to dark golden brown or straw-coloured tinged red-brown; spikelets suberect or spreading in loose hemispherical to globose clusters | 12 |
| Perennials with slender, creeping rhizomes producing fibrous-coated tubers 5–10 mm diam.; glumes orange-brown to dark red-brown or yellow-brown, with narrow hyaline or whitish margins; spikelets spreading in short, broad-cylindrical spikes
Back to 10 | 16 |
| 12 | Glumes pale red-brown with broad white or yellowish margins; spikelets suberect and held close to rachis in long, narrow-cylindrical spikes; leaves not septate-nodulose | Cyperus nutans |
| Glumes yellow-brown to dark golden brown or straw-coloured tinged red-brown; spikelets spreading in loose hemispherical to globose clusters; leaves often septate-nodulose
Back to 11 | 13 |
| 13 | Spikelets 1.2–2 mm wide in side view; inflorescence compound; nut very narrow-ellipsoid | Cyperus betchei |
| Spikelets 2–4.5 mm wide in side view; inflorescence simple or with a few secondary branches; nut obovoid or narrow-obovoid to broad-ellipsoid
Back to 12 | 14 |
| 14 | Nut grey to black; glumes with excurved mucro 0.3–0.8 mm long | Cyperus clarus |
| Nut yellow-brown; glumes with straight mucro
Back to 13 | 15 |
| 15 | Glumes with mucro 0.1–0.3 mm long; perennial; leaf and involucral bract margins with more or less irregularly spaced and shaped prickles; on sandy-loam soils | Cyperus fulvus |
| Glumes with mucro 0.2–0.5 mm long; annual or short-lived perennial; leaf and involucral bracts with more or less regular antrorsely aculeate prickles; on clayey soils
Back to 14 | Cyperus isabellinus |
| 16 | Culms terete below, trigonous near the apex; leaves rarely half as long as culms; lowest involucral bract erect, very much exceeding the inflorescence, usually pushing it to one side; nut when mature 2–3 times as long as broad; freely fruiting | Cyperus victoriensis |
| Culms trigonous throughout their length; leaves mostly a half to three-quarters as long as culms; inflorescence symmetrical; nut either c. 1.5 times as long as broad or rarely maturing
Back to 11 | 17 |
| 17 | Rachis of spikes often spinulose; spikelets 5–12 mm long, obtuse; glumes yellow to dark golden brown, 3–5-nerved on each side, very obtuse; tubers globose to ovoid, with grey tomentum at maturity;rhizomes yellow-brown | Cyperus esculentus |
| Rachis of spikes usually not spinulose (occasionally sparsely so); spikelets 10–30 mm long, acute or obtuse; glumes red-brown to dark red-brown, with up to 3 nerves on each side, obtuse or acute;tubers more or less ellipsoid, without tomentum; rhizomes purplish to dark brown
Back to 16 | 18 |
| 18 | Lowest involucral bract shorter or not much longer than the inflorescence; spikelets c. 2 mm wide when mature; glumes usually dark red-brown, obtuse; the midrib faintly curved and recurved in side view from base to apex; fruit rarely maturing; fibrous coats of tubers soon disintegrating, not usually persisting beyond the first year | Cyperus rotundus |
| Lowest bract much exceeding the inflorescence; spikelets 2.5–3 mm wide in side view when mature; glumes various shades of brown, rarely very dark, acute; midrib straight in side view from immediately above the base to the apex; nut c. 1.5 times as long as broad, obovate to elliptic-obovate; freely fruiting; fibrous coats of tubers often persisting into the second year
Back to 17 | Cyperus bifax |
| 19 | Inflorescence compound; glumes yellow-brown; nut 1.9–2.2 mm long, nearly as long as glume | Cyperus betchei |
| Inflorescence simple; glumes red-brown or greenish tinged red-brown; nut 1.2–1.7 mm long, about half as long as glume
Back to 10 | Cyperus subulatus |
| 20 | Glumes 1–1.5 mm long | Cyperus exaltatus |
| Glumes 2–6.5 mm long
Back to 9 | 21 |
| 21 | Leaves and bracts septate-nodulose (often only obvious when dried) | 22 |
| Leaves not septate-nodulose
Back to 20 | 24 |
| 22 | Terminal spikes cylindrical or ovate-cylindrical, laterals smaller, divergent or deflexed | 23 |
| Terminal spikes hemispherical to globose, usually dense, 1–2 cm wide in side view; glumes 2–2.5(–3) mm long
Back to 21 | Cyperus gunnii |
| 23 | Glumes 4–6.5 mm long, red-brown; spikelets 4–10-flowered | Cyperus lucidus |
| Glumes 2.5–4 mm long, pale brown; spikelets 2–5-flowered
Back to 22 | Cyperus vorsteri |
| 24 | Spikelets 10–28 mm long, 8–24-flowered; tufted perennial, often apparently annual, often without any rhizome | Cyperus congestus |
| Spikelets 6–15 mm long, 7–14-flowered; rhizomatous perennial; rhizome short and thick
Back to 21 | 25 |
| 25 | Glumes pale red-brown, with midrib green, 2–2.5 mm long; spikelets suberect, 1.5–2.0 mm wide in side view | Cyperus nutans |
| Glumes whitish to pale brown on the sides, 3–3.5 mm long; spikelets spreading, 2–2.5 mm wide in side view
Back to 24 | Cyperus rigens |
| 26 | Glumes obtuse in side view but sometimes apparently acute because of the presence of a short mucro | 27 |
| Glumes more or less acute in side view
Back to 7 | 30 |
| 27 | Glumes 1–2 mm long; spikelets flattened; tufted annual | Cyperus iria |
| Glumes 2–3.5 mm long; spikelets flattened or terete; rhizomatous perennials
Back to 26 | 28 |
| 28 | Glumes without broad whitish margins, short-mucronate; bracts and leaves septate-nodulose in the dried state, thick-textured; spikes rather dense | 29 |
| Glumes with broad whitish margins above; bracts and leaves not septate-nodulose, thin-textured; spikes broad-ovoid, loose
Back to 27 | Cyperus procerus |
| 29 | Nut red-brown, minutely tuberculate; leaves to 12 mm wide | Cyperus alterniflorus |
| Nut yellow-brown, smooth to colliculate; leaves to 7 mm wide
Back to 28 | Cyperus gunnii |
| 30 | Rachis minutely and densely hispid | Cyperus pilosus |
| Rachis not hispid
Back to 26 | 31 |
| 31 | Glumes white to dark golden brown or straw-coloured tinged red-brown | 32 |
| Glumes red-brown
Back to 30 | 35 |
| 32 | Glumes with excurved mucro 0.3–1 mm long | 33 |
| Glumes without mucro, or mucro straight and no more than 0.3 mm long
Back to 31 | 34 |
| 33 | Nut less than half as long as glume; annual with thin-textured leaves and bracts, not septate-nodulose | Cyperus compressus |
| Nut at least half as long as glume; slender perennial with tough-textured leaves and bracts, often obviously septate-nodulose when dried
Back to 32 | Cyperus clarus |
| 34 | Nut yellow-brown, nearly as long as glume; glumes 2–3 mm long; leaves and bracts tough-textured, often obviously septate-nodulose when dried | Cyperus fulvus |
| Nut dark red-brown, less than half as long as glume; glumes 3–3.5 mm long; leaves and bracts thin-textured, not septate-nodulose
Back to 32 | Cyperus rigens |
| 35 | Leaves and bracts tough-textured, flat or folded, margins and midribs scabrous; lowest involucral bract suberect; rhizomatous perennial with solitary culms | Cyperus lhotskyanus |
| Leaves and bracts thin-textured, flat or with revolute margins; lowest involucral bracts spreading; tufted perennial, often apparently annual and without a rhizome
Back to 31 | Cyperus congestus |
| 36 | Involucral bracts all much shorter than inflorescence; plant resembling miniature papyrus | Cyperus prolifer |
| One to 22 involucral bracts longer than inflorescence; plants not resembling miniature papyrus
Back to 5 | 37 |
| 37 | Involucral bracts 6–22 exceeding inflorescence (rarely only as long as inflorescence) | 38 |
| Involucral bracts 1–5 exceeding inflorescence
Back to 36 | 45 |
| 38 | Leaves all or mostly reduced to sheaths | 39 |
| Leaves with well-developed blade
Back to 37 | 41 |
| 39 | Involucral bracts 12–22 exceeding inflorescence; glumes c. 2 mm long | Cyperus involucratus |
| Involucral bracts 6–9 exceeding or as long as inflorescence; glumes 1–2.5 mm long
Back to 38 | 40 |
| 40 | Glumes 2–2.5 mm long | Cyperus vaginatus |
| Glumes 1–1.3 mm long
Back to 39 | Cyperus filipes |
| 41 | Inflorescence with few (1–9, rarely to 15 in Cyperus vaginatus) spikelets per loose cluster | 42 |
| Inflorescence with numerous spikelets per dense globose cluster
Back to 38 | 44 |
| 42 | Leaves with 2 prominent, whitish (at least when dried) lateral veins; glumes straw-coloured to pale brown, 1–1.5 mm long; rachilla winged; leaf sheaths purplish red at base | Cyperus albostriatus |
| Leaves with only midvein prominent; glumes red-brown to blackish; rachilla not winged; leaf sheaths purplish red or pale yellow-brown at base
Back to 41 | 43 |
| 43 | Nut ellipsoid; leaf sheaths purplish red at base; glumes very dark red-brown to blackish, 1.5–2 mm long | Cyperus tetraphyllus |
| Nut ovoid; leaf sheaths pale yellow-brown at base; glumes red-brown, 3–3.5 mm long
Back to 42 | Cyperus rupicola |
| 44 | Inflorescence with numerous branches; culms 25–90 cm high | Cyperus eragrostis |
| Inflorescence head-like; culms 1–20 cm high
Back to 41 | Cyperus pygmaeus |
| 45 | Leaves all or mostly reduced to sheaths with a rudimentary blade | 46 |
| Leaves with well-developed blade
Back to 37 | 48 |
| 46 | Culms and involucral bracts firm to rigid; culms terete to trigonous | 47 |
| Culms and involucral bracts soft-textured (easily compressed between the fingers); culms triquetrous
Back to 45 | Cyperus haspan |
| 47 | Involucral bracts mostly 5–8 in number, always more than 5 cm and up to 15 cm long, flat, firm-textured, not pungent; inflorescence simple to compound with 4–12 branches to 6 cm long, bearinghemispherical clusters of spikelets, or occasionally loosely head-like | Cyperus vaginatus |
| Involucral bracts 2–4, usually less than 5 cm long, very rigid and pungent with incurved margins; inflorescence head-like or with 1–3 short branches to 2 cm long, bearing globose clusters ofspikelets
Back to 46 | Cyperus gymnocaulos |
| 48 | Nut trabeculate and striate | Cyperus mirus |
| Nut smooth or minutely roughened
Back to 45 | 49 |
| 49 | Glumes less than 2 mm long (excluding any long mucro) | 50 |
| Glumes 2 mm or more long (excluding any long mucro)
Back to 48 | 73 |
| 50 | Glumes with sides evenly red-brown to dark red-brown or blackish (midribs mostly green) | 51 |
| Glumes uniformly green or with sides hyaline, white, pale brown, yellow or golden brown, occasionally with a red-brown patch (midribs mostly green)
Back to 49 | 59 |
| 51 | Rachilla winged | Cyperus rigidellus |
| Rachilla not winged
Back to 50 | 52 |
| 52 | Spikelets numerous in the dense globose clusters | 53 |
| Spikelets few (1–12) in the loose, ovoid to hemispherical clusters
Back to 51 | 55 |
| 53 | Glumes 0.6–0.9 mm long | Cyperus difformis |
| Glumes at least 1.0 mm long
Back to 52 | 54 |
| 54 | Glumes 1.5–2 mm long | Cyperus reflexus |
| Glumes 1.0–1.4 mm long
Back to 53 | Cyperus castaneus |
| 55 | Annual | Cyperus castaneus |
| Perennial
Back to 52 | 56 |
| 56 | Glumes red-brown | Cyperus haspan |
| Glumes dark red-brown to blackish
Back to 55 | 57 |
| 57 | Inflorescence compound; nut c. 0.5 mm long, less than half as long as glume | Cyperus concinnus |
| Inflorescence simple; nut 1.3–1.5 mm long, nearly as long as glume
Back to 56 | 58 |
| 58 | Glumes acute, dorsally straight in side view | Cyperus disjunctus |
| Glumes obtuse, shortly mucronate, dorsally strongly curved in side view
Back to 57 | Cyperus tetraphyllus |
| 59 | Inflorescence compound to decompound with numerous clusters of spikelets; glumes evenly yellow to golden brown; leaves strongly septate-nodulose, thick-textured; robust perennial | Cyperus dactylotes |
| Inflorescence simple with 1–8 clusters of spikelets; glumes not evenly yellow to golden brown (occasionally with yellowish patches); leaves not or rarely slightly septate-nodulose but then thin-textured; slender perennials or annuals
Back to 50 | 60 |
| 60 | Glumes with 2–6 nerves on each side | 61 |
| Glumes with 1 nerve or no nerves on each side
Back to 59 | 66 |
| 61 | Spikelets with upper flowers female, lower flowers male | Cyperus semifertilis |
| Spikelets with all flowers usually bisexual
Back to 60 | 62 |
| 62 | Involucral bract 1, erect; inflorescence of 1–4 spikelets; dwarf annual | Isolepis levynsiana |
| Involucral bracts 2–4, erect to spreading; inflorescence with 1–25 spikelets; small perennials or annuals
Back to 61 | 63 |
| 63 | Spikelets 2.5–4 mm wide in side view; nut pale brown | Cyperus rigidellus |
| Spikelets 2–2.5 mm wide in side view; nut dark brown
Back to 62 | 64 |
| 64 | Glumes strongly excurved; inflorescence of 1–5 spikelets | Cyperus sculptus |
| Glumes dorsally slightly incurved in side view to slightly excurved; inflorescence of 12–25 spikelets
Back to 63 | 65 |
| 65 | Nut broad-obpyriform to broad-obovoid, with globose bulge near base of persistent style base | Cyperus enervis |
| Nut ellipsoid to broad-ellipsoid, without persistent dilated style base
Back to 64 | Cyperus eglobosus |
| 66 | Keel of glumes a broad band about as wide as thinner-textured side of glume | 67 |
| Keel of glumes a narrow band, much narrower than sides of glume
Back to 60 | 70 |
| 67 | Tufted annuals; midrib of glumes with larger, more isodiametric cell outlines than on sides | 68 |
| Perennials, shortly rhizomatous, often with fibrous remains of leaf sheaths at base; midrib and sides of glumes with similar cell outlines
Back to 66 | 69 |
| 68 | Spikelets 2–2.5 mm wide in side view; glumes 1–1.5 mm long | Cyperus flaccidus |
| Spikelets c. 3 mm wide in side view; glumes 1.5–2 mm long
Back to 67 | Cyperus aquatilis |
| 69 | Glumes c. 1.5 mm long, longer than broad; stamens 3 | Cyperus trinervis |
| Glumes 1–1.3 mm long, about as long as broad; stamens 2
Back to 67 | Cyperus stradbrokensis |
| 70 | One involucral bract longer than inflorescence; base of style inconspicuous (not thickened) | 71 |
| Two to four involucral bracts longer than inflorescence; base of style thickened compared to rest of style and obviously persistent on fruit
Back to 66 | 72 |
| 71 | Glumes more or less straight dorsally from shortly above base in side view, 1.7–2 mm long, 0.7–1 mm wide in side view; inflorescence usually a single sessile cluster of spikelets (rarely with 1 or 2 very short branches) | Cyperus laevis |
| Glumes strongly curved dorsally in side view, with excurved apex, 1.5–1.7 mm long, c. 0.5 mm wide in side view; inflorescence usually with 1–4 short branches
Back to 70 | Cyperus imbecillis |
| 72 | Base of style erect; nut broad-obovoid, nearly as long as the glume; glume keel smooth | Cyperus enervis |
| Base of style strongly recurved; nut ellipsoid, c. 2/3 as long as glume; glume keel minutely toothed towards apex
Back to 70 | Cyperus curvistylis |
| 73 | Nut with paler corky, thickened angles | Cyperus platystylis |
| Nut without corky, thickened angles
Back to 49 | 74 |
| 74 | Nut ovoid | Cyperus rupicola |
| Nut obovoid to ellipsoid
Back to 73 | 75 |
| 75 | Glumes with sides uniformly yellow to red-brown | 76 |
| Glumes with sides uniformly green, whitish, pale brown, or with red-brown patch
Back to 74 | 89 |
| 76 | Glumes with midrib about as wide as sides and with cell outlines larger than on sides, 1-nerved only at edge of midrib | Cyperus eragrostis |
| Glumes with midrib much narrower than sides and with cell outlines similar to those of sides, with 2–4 nerves on each side
Back to 75 | 77 |
| 77 | Leaves and bracts strongly curly at least near apex | 78 |
| Leaves and bracts straight to slightly curved
Back to 76 | 81 |
| 78 | Anthers 1.3–1.6 mm long; glume mucro no more than 0.1 mm long | Cyperus secubans |
| Anthers 0.3–1.2 mm long; glume mucro 0.1–0.8 mm long
Back to 77 | 79 |
| 79 | Glumes evenly yellow to golden brown, with mucro 0.3–0.8 mm long (usually excurved); nut grey to black | Cyperus clarus |
| Glumes straw-coloured to golden brown and with dull red-brown patches, with straight mucro 0.1–0.3 mm long; nut pale yellow-brown
Back to 78 | 80 |
| 80 | Leaf marginal prickles erect, papillose; leaf sheaths pinkish to purple-red; nut tuberculate or colliculate | Cyperus rigidellus |
| Leaf marginal prickles either mixed strongly flabellate to erect aculeate or antrorsely aculeate; leaf sheaths pale yellowish with red-brown blotches; nut colliculate to smooth and reticulate-areolate
Back to 79 | Cyperus fulvus |
| 81 | Nut red-brown to black or grey, tuberculate (occasionally smooth in Cyperus gilesii) | 82 |
| Nut yellow-brown to dark golden brown, smooth to colliculate or pitted
Back to 77 | 84 |
| 82 | Anthers 1.1–1.8 mm long; nut narrow-ellipsoid to narrow-obovoid, red-brown | Cyperus alterniflorus |
| Anthers 0.3–0.8 mm long; nut very narrow-ellipsoid or obovoid, red-brown to blackish or grey to black
Back to 81 | 83 |
| 83 | Nut very narrow-ellipsoid, red-brown to blackish; glumes very narrow-elliptic to narrow-ovate | Cyperus gilesii |
| Nut obovoid, grey to black; glumes elliptic to ovate
Back to 82 | Cyperus clarus |
| 84 | Prickles on leaf margins antrorsely aculeate, more or less regularly spaced | 85 |
| Prickles on leaf margins mixed aculeate to papillose, antrorse to erect and flabellate, more or less irregularly spaced
Back to 81 | 87 |
| 85 | Glumes dark red-brown or rarely straw-coloured; spikelet clusters dense; leaves exceeding or as long as culms | Cyperus gunnii |
| Glumes yellow to dark golden brown; spikelet clusters loose; leaves shorter than to as long as culms
Back to 84 | 86 |
| 86 | Glumes 2.5–3.4 mm long; glume spacing 1.6–2.3 mm | Cyperus betchei |
| Glumes 1.3–2.1 mm long; glume spacing 0.9–1.3 mm
Back to 85 | Cyperus dactylotes |
| 87 | Anthers 0.3–1.2 mm long | Cyperus fulvus |
| Anthers 1.3–2.0 mm long
Back to 84 | 88 |
| 88 | Long-rhizomatous, with culms usually solitary along rhizome; leaves V-shaped in cross section, with midrib obvious abaxially, with marginal prickles irregularly spaced; plants never viscid | Cyperus lhotskyanus |
| Very shortly rhizomatous, with culms tufted; leaves canaliculate, with midrib not obvious, with marginal prickles regularly spaced; plants often viscid
Back to 87 | Cyperus secubans |
| 89 | Spikelets less than 2.5 mm wide in side view | 90 |
| Spikelets 2.5–5 mm wide in side view
Back to 75 | 92 |
| 90 | Inflorescence a single cluster of 1–14 spikelets | 91 |
| Inflorescence simple to compound, with 3–8 primary branches and numerous spikelets
Back to 89 | Cyperus fulvus |
| 91 | Glumes 3- or 4-nerved on each side; apex excurved in side view | Cyperus gracilis |
| Glumes 1- or 2-nerved on each side; apex more or less straight in side view
Back to 90 | Cyperus enervis |
| 92 | Glumes with midrib about as wide as sides and with cell outlines larger than on sides, nerved only at edge of midrib | Cyperus eragrostis |
| Glumes with midrib much narrower than sides and with cell outlines similar to those of sides, with 2–4 nerves on each side
Back to 89 | 93 |
| 93 | Nut dark brown to black, less than half as long as glume; leaves never curly; plant never viscid | Cyperus compressus |
| Nut pale yellow-brown, three-quarters to seven-eighths as long as glume; leaves often curly towards apex; plants occasionally viscid
Back to 92 | 94 |
| 94 | Culms 3–25 cm long; leaves not septate-nodulose; leaf sheaths pinkish to purple-red near base | Cyperus rigidellus |
| Culms 25–50 cm long; leaves mostly septate-nodulose; leaf sheaths pale yellowish or straw-coloured with occasional red-brown patches
Back to 93 | Cyperus fulvus |
| 95 | Inflorescence of 1–6 sessile spikes, rarely with 1–3 short branches to 1.5 cm long | 96 |
| Inflorescence simple or compound with spikes on 3–14 branches to 20 cm long (rarely head-like in Cyperus leiocaulon)
Back to 4 | 97 |
| 96 | Bases of culms bulbously swollen; glumes acute; flowers 1–3 per spikelet | Cyperus aggregatus |
| Bases of culms apparently enlarged for some distance because of persistent, whitish, thin-textured leaf sheaths; glumes obtuse; flowers 3–6 per spikelet
Back to 95 | Cyperus dubius |
| 97 | Culms and axes of inflorescence hispid or papillose-scabrous | 98 |
| Culms and axes of inflorescence smooth
Back to 95 | 99 |
| 98 | Culms and rachis of inflorescence hispid-scabrous, green; leaves septate-nodulose | Cyperus scaber |
| Culms and rachis of inflorescence papillose-scabrous, greyish; leaves not septate-nodulose
Back to 97 | Cyperus conicus |
| 99 | Spikelets c. 0.5 mm diam. when mature | 100 |
| Spikelets 0.7–2.5 mm diam. when mature
Back to 97 | 102 |
| 100 | Glumes 2.3–2.7 mm long; spikelets 3–6-flowered; base of culms not enlarged | 101 |
| Glumes 3–3.5 mm long; spikelets 1–3-flowered; base of culms bulbously enlarged
Back to 99 | Cyperus cyperoides |
| 101 | Spikelets spreading at 90–140° from the vertical; culms rigid, erect, 2–4 mm diam. | Cyperus dietrichiae |
| Spikelets spreading at 40–90° from the vertical; culms lax, c. 1 mm diam.
Back to 100 | Cyperus bowmannii |
| 102 | Spikelets breaking up at maturity and dispersing as individual corky internodes of the rachilla with associated glume and nut | Cyperus odoratus |
| Spikelet falling as a complete unit at maturity
Back to 99 | 103 |
| 103 | Leaves strongly septate-nodulose; robust perennials to c. 170 cm tall; inflorescence compound; involucral bracts (5-)8–13 exceeding inflorescence | 104 |
| Leaves not septate-nodulose; slender perennials to c. 50 cm tall; inflorescence simple; involucral bracts 1–8 exceeding inflorescence
Back to 102 | 105 |
| 104 | Glumes 2.5–4 mm long, pale brown; nut 1.8–2.3 mm long, dark yellow-brown; spikelets 2.5–5 mm long, 2–5-flowered | Cyperus vorsteri |
| Glumes 4–6.5 mm long, red-brown to dark red-brown; nut 2.5–3 mm long, dark grey-brown to blackish; spikelets 4–20 mm long, 4–10-flowered
Back to 103 | Cyperus lucidus |
| 105 | Involucral bracts 2 exceeding inflorescence; flowers 5–16 per spikelet | Cyperus subulatus |
| Involucral bracts 3–5 exceeding inflorescence; flowers 2–4 per spikelet
Back to 103 | Cyperus leiocaulon |
| 106 | Spikelets several- to numerous-flowered | 107 |
| Spikelets 1-flowered, but sometimes with a second imperfect flower above, whole spikelet falling as a unit at maturity
Back to 1 | 115 |
| 107 | Each spikelet falling as a unit at maturity | Cyperus bracheilema |
| Each spikelet with rachilla persistent and glumes falling individually at maturity
Back to 106 | 108 |
| 108 | Inflorescence pseudolateral, sessile; lowest involucral bract erect, appearing as a continuation of the rush-like culm | Cyperus laevigatus |
| Inflorescence obviously terminal, branched or head-like; involucral bracts not as above
Back to 107 | 109 |
| 109 | Nut dorsally flattened with a flat or concave face against the rachilla; inflorescence densely head-like, subglobose, with 5–7 or more involucral bracts exceeding inflorescence | Cyperus pygmaeus |
| Nut laterally flattened, with one edge against the rachilla; inflorescence loosely head-like or branched, with 1–4 involucral bracts exceeding inflorescence
Back to 108 | 110 |
| 110 | Glumes 3.5–4.5 mm long, acute; spikelets 3.5–5 mm wide in side view | Cyperus unioloides |
| Glumes less than 3 mm long, obtuse (occasionally broad-acute in Cyperus polystachyos); spikelets 1–3 mm wide in side view
Back to 109 | 111 |
| 111 | Glumes with excurved mucro 0.3–0.7 mm long; glume-spacing c. 0.5 mm | Cyperus nervulosus |
| Glumes not mucronate or scarcely mucronulate; glume-spacing c. 1 mm
Back to 110 | 112 |
| 112 | Glumes incurved dorsally in side view, dark red-brown to blackish, often with a hyaline patch on sides | Cyperus sanguinolentus |
| Glumes more or less straight dorsally in side view, yellow to very dark yellow-brown, occasionally red-brown in Cyperus polystachyos and C. flavidus but never with a hyaline patch
Back to 111 | 113 |
| 113 | Spikelets suberect, usually densely crowded in obconical subdigitate clusters; rachilla narrowly winged | Cyperus polystachyos |
| Spikelets spreading widely, in loose, shortly spicate to subdigitate clusters; rachilla not winged
Back to 112 | 114 |
| 114 | Nut with faint whitish transverse wrinkles | Cyperus flavescens |
| Nut minutely puncticulate
Back to 113 | Cyperus flavidus |
| 115 | Tufted annual or perennial with or without a very short rhizome; inflorescence whitish or very light green; nut black at maturity; stamens 2 | Cyperus sesquiflorus |
| Perennial with creeping rhizomes, to 30 cm long but occasionally very short; inflorescence greenish or yellow-tinged; nut yellowish becoming brown at maturity
Back to 106 | 116 |
| 116 | Inflorescence more or less ovoid, dense, solitary or with 2 smaller ones at the base; spikelets numerous, sometimes 100 in number, 1-flowered; midrib of the glumes usually toothed; stamens 1 or 2 (rarely 3) | Cyperus brevifolius |
| Inflorescence globose, loose, always solitary; spikelets not usually more than 50, a second imperfect flower often present; midrib of the glumes usually smooth or nearly so, rarely toothed; stamens 3 (rarely 2)
Back to 115 | Cyperus sphaeroideus |
