Contains 55 accepted taxa overall.
Characteristics
Cyperus has recently been expanded to include Kyllinga, Lipocarpha, and Oxycaryum (Larridon et al. 2011; Larridon et al. 2013; Bauters et al. 2014).
Classification
Citation
CYPERUS Linnaeus, Sp. Pl. 44. 1753.
-
TYPE: Cyperus esculentus Linnaeus 1753. Lectotypified by Britton, Bull. Dept. Agric. Jamaica 5(suppl. 1): 6. 1907.
Species
| Scientific Name | Common Name | Herbarium Specimens | Status | Photos |
|---|---|---|---|---|
| Cyperus articulatus | Jointed Flatsedge | |||
| Cyperus bipartitus | Slender Flatsedge, Shining Flatsedge | |||
| Cyperus blepharoleptos | Cuban-bulrush | |||
| Cyperus brevifolioides | Asiatic Greenhead Sedge | |||
| Cyperus brevifolius | Perennial Greenhead Sedge | |||
| Cyperus compressus | Poorland Flatsedge | |||
| Cyperus croceus | Baldwin’s Flatsedge | |||
| Cyperus cuspidatus | Coastal Plain Flatsedge | |||
| Cyperus dentatus | Toothed Flatsedge | |||
| Cyperus difformis | Variable Flatsedge, Smallflower Umbrella Sedge | |||
| Cyperus distinctus | Swamp Flatsedge | |||
| Cyperus drummondii | Drummond's Sedge | |||
| Cyperus echinatus | Globe Flatsedge | |||
| Cyperus entrerianus | Deep-rotted sedge, Woodrush flatsedge | |||
| Cyperus eragrostis | Tall Flatsedge | |||
| Cyperus erythrorhizos | Redroot Flatsedge | |||
| Cyperus esculentus var. leptostachyus | Yellow Nutsedge, Yellow Nutgrass, Wild Chufa, Earth-almond | |||
| Cyperus esculentus var. macrostachyus | Yellow Nutsedge, Yellow Nutgrass, Wild Chufa, Earth-almond | |||
| Cyperus filicinus | Fern Flatsedge | |||
| Cyperus filiculmis | Southeastern Flatsedge | |||
| Cyperus flavescens | Yellow Flatsedge | |||
| Cyperus flavicomus | White-edged Flatsedge | |||
| Cyperus granitophilus | Granite Flatsedge | |||
| Cyperus grayi | Gray’s Flatsedge | |||
| Cyperus haspan | Sheathed Flatsedge | |||
| Cyperus hortensis | Annual Greenhead Sedge | |||
| Cyperus hystricinus | Bristly Flatsedge | |||
| Cyperus involucratus | Umbrella-plant | |||
| Cyperus iria | Rice-field Flatsedge | |||
| Cyperus lancastriensis | Many-flowered Flatsedge | |||
| Cyperus lanceolatus | Epiphytic flatsedge | |||
| Cyperus lecontei | Leconte's Flatsedge | |||
| Cyperus leptocarpus | ||||
| Cyperus lupulinus var. lupulinus | Great Plains Flatsedge | |||
| Cyperus lupulinus var. macilentus | Great Plains Flatsedge | |||
| Cyperus metzii | Crested Greenhead Sedge | |||
| Cyperus neotropicalis | American Lipocarpha | |||
| Cyperus odoratus var. odoratus | Fragrant Flatsedge | |||
| Cyperus ovatus | Ovateleaf Flatsedge | |||
| Cyperus oxylepis | Sharpscale Flatsedge | |||
| Cyperus pilosus | Fuzzy Flatsedge | |||
| Cyperus plukenetii | Starburst Flatsedge, Plukenet’s Flatsedge | |||
| Cyperus polystachyos | Coast Flatsedge | |||
| Cyperus pseudovegetus | Green Flatsedge, Marsh Flatsedge | |||
| Cyperus refractus | Reflexed Flatsedge | |||
| Cyperus retrofractus | Rough Flatsedge | |||
| Cyperus retrorsus | Pineland Flatsedge | |||
| Cyperus rotundus | Purple Nutsedge, Nutgrass, Cocograss | |||
| Cyperus sesquiflorus | Whitehead Sedge. | |||
| Cyperus squarrosus var. squarrosus | Awned Flatsedge | |||
| Cyperus subsquarrosus | Smallflower Halfchaff | |||
| Cyperus surinamensis | Tropical Flatsedge | |||
| Cyperus tetragonus | Four-angled Flatsedge | |||
| Cyperus thyrsiflorus | Cyperus thyrsiflorus | |||
| Cyperus virens | Green Flatsedge |
Identification Key
1. Scales spirally arranged
2
1. Scales distichous
4
2. Leaves 0.2-2 mm wide; spikelet scales 0.1-0.5 mm wide; perianth of 1-2 hyaline scales (former Lipocarpha)
2. Leaf blades 2-7 mm wide; spikelet scales 0.5-2.5 mm wide; perianth absent
3
3. Culms to 100 cm long, with leaves primarily basal; leaves 30-110 cm long; leaf ligule present, ciliate; style 2-fid (former Oxycaryum)
3. Culms to 12 cm long, densely leafy throughout; leaves 3-8 cm long; leaf ligule absent; style 3-fid (former Remirea)
4. Inflorescence of 1–4 spikes, sessile; spikelets with 1–3 scales; styles 2-fid; achene lenticular (former Kyllinga)
4. Inflorescence with 1-many arrays of 1-many spikes, sessile or pedunculate; spikelets with 5–76 scales; styles 2- or 3-fid; achene lenticular or trigonous
5
5. Stigmas 2; achenes biconvex (Pycreus group)
5. Sitgmas 3; achenes trigonous or terete
6
6. Spikelet disarticulating into 1-fruited segments (scale, internode, and rachilla wings) (Diclidium group)
6. Spikelet not disarticulating into 1-fruited segments
7
7. Leaves lacking blades, or blades rarely to 9 mm long
7. Leaves with conspicuous blades
8
8. Spikelets digitate or pseudowhorled, borne from the same point or appearingly so, internodes unapparent between the spikelets, rachis 0-2.5 mm long
9
8. Spikelets dense to sparse along a prolonged or elongate rachis, spicate or racemose, rachis 3-25 mm long
10
9. Spikelet scales 1-keeled longitiudinally or rounded
9. Spikelet scales 2-keeled and longitudinally flattened or depressed along the middle
10. Spikelets with most (middle and proximal ones) descending at a downward angle, only the few distalmost spreading
10. Spikelets with most spreading to ascending, not regularly pointing downward or only a few proximal ones descending
11
11. Spikelets overlapping, densely spicate and radiating in nearly all directions; floral scales 2-5(7) per spikelet
11. Spieklets spaced between distally and proximally adjacent ones, loosely spicate or paniculate, semi-distichous or loosely spiraled around the rachis; floral scales 2-30 per spikelet
1. (Key A, formerly genus Lipocarpha) Leaves 1-2 mm wide; spikes (1)3-6, terminal, the bracts spreading; anthers 0.5 mm (Lipocarpha maculata)
1. Leaves 0.3-0.6 mm wide; spikes (1)2-3, appearing lateral with the an erect bract continuous with the culm; anthers 0.1-0.2 mm long
2
2. Outer scales contracted into an awn subequal to longer than the scale body; stigmas 3 (Lipocarpha squarrosa)
2. Outer scales apiculate; stigmas 2 (Lipocarpha micrantha)
1. (Key B, formerly genus Kyllinga) Floral scale winged, laciniate; anthers 2 mm long (Kyllinga squamulata)
1. Floral scale ciliate or glabrous, not winged; anthers 0.2-1.2 mm long
2
2. Spikes white
3
2. Spikes green
4
3. Plant with slender, delicate stolons; central spike hemispherical to pyramidal; achene brown (Kyllinga bulbosa)
3. Plant cespitose; central spike cylindric; achene black (Kyllinga odorata)
4. Plant rhizomatous; anthers 0.8-1.1 mm long
4. Plant cespitose; anthers 0.2-0.4 mm long (Kyllinga pumila)
1. (Key C, Pycreus group). Spikelets with 3-6 floral scales, the scales with several longitudinal veins
1. Spikelets with (4)6-54 floral scales, the scales mostly with 1 veins on either side
2
2. Floral scales 3-4 mm long
2. Floral scales 1-2.5 mm long
3
3. Floral scales with erect to recurved awn, the awn 0.3-0.5 mm long
3. Floral scales without an awn, merely acute to acuminate
4
4. Culms 1.5-2.5 m tall; inflorescence bracts 20-100 cm long; achene dorsiventrally flattened, borne with face toward rachilla
4. Culms 0.1-0.8 m tall; inflorescence bracts 1-35 cm long; achene laterally flattened, biconvex, or subcylindric, borne with edge toward rachilla
5
5. Inflorescence bracts (2)8-35 cm long; spikelet with floral scales distant, not overlapping or scarcely overlapping; floral scales with clear or hyaline border
5. Inflorescence bracts 2-15(23) cm long; spikelet with floral scales imbricate, closely overlapping; floral scales with a yellowish, brownish, or greenish border
6
6. Achene linear-oblong, 0.4-0.5(0.6) mm wide, 2-2.5 times longer than wide
6. Achene ellipsoid to obovoid, (0.5)0.6-0.8 mm wide, 1.3-2 times longer than wide
7
7. Floral scales light to dark brown or purplish, usually at least partly dark brown or purplish; stigmas 1-1.5 mm long; achene black
7. Floral scales yellowish to greenish or partly pale brown; stigmas 0.5-1 mm long; achene black to brown
8
8. Cespitose annual; stamens 3; achene black or dark purplish
8. Rhizomatous perennial; stamens 2; achene brown
1. (Key D, Diclidium) Culms 0.5-1 mm wide; leaves 0.5-2 mm wide; inflorescence bracts 0.5-1 mm wide, longest one erect; spikelet clusters usualy subsessile, spikelets digitate or nearly so
1. Culms (0.5)1-4 mm wide; leaves 4-12 mm wide; inflorescence bracts 1-14 mm wide, longest spreading to ascending; spikelet clusters pedunculate, spikelets on an elongate rachis
1. (Key E) Primary inflorescence bracts 2-3(4)
2
1. Primary inflorescence bracts 20-100
4
2. Culm (4)7-20 mm wide, distinctly septate; spikelets in spicate clusters
2. Culm 2-8 mm wide, not noticeably septate; spikelets in digitate clusters
2
3. Primary inflorescence branches 5-50, mostly linear, usually of varying lenghts, immature spikelets early apparent; anthers 0.3-0.5 mm long
3. Primary inflorescence branches 50-250, mostly filiform, mostly all elongate and subequal in length, greatly elongate and often appearing naked before immature spikelets arise; peduncles subtending spikelet clusters filiform anthers 1-1.2 mm long
4. Primary inflorescence bracts 15-30, these 15-40 cm long; spikelets in digitate clusters, these subtended by short bracts 3-10 mm long
4. Primary inflorescence bracts 4-12, these 3-45 cm long; spikelets in spicate clusters, these subtended by elongate bracts 15-250 mm long
5
5. Primary inflorescence bracts (8)20–45 cm long; primary inflorescence branches stiff, ascending to erect; spikelet clusters subtended by linear bracts, 1.5-5 mm wide
5. Primary inflorescence bracts 3–8 cm long; primary inflorescence branches slender, drooping or arching; spikelet clusters subtended by filiform bracts, 0.5-2 mm wide
1. (Key F) Annuals
2
1. Perennials
5
2. Floral scales (2.4)2.6-3 mm long; achene 1-1.5 mm long
2. Floral scales 0.6-2.2 mm long; achene 0.5-0.8(1.1) mm long
3
3. Floral scale apex truncate to obtuse, scarcely if at all mucronulate
3. Floral scale apex recurved
4
4. Floral scale with 1 lateral vein per half, the apex emarginate or retuse with a cupsidate awn
4. Floral scale with 3-4 lateral veins per half, the apex acuminate or attenuate
5. Rhizomatous; leaves 2-15 mm wide
6
5. Cespitose; leaves 1-4 mm wide
7
6. Leaf blades and inflorescence bracts with 3(-5) major veins, these 3-15 mm wide; primary inflorescence bracts 8-14
6. Leaf blades and inflorescence bracts with 1 major vein, these 1-5 mm wide; primary inflorescence bracts 3-5
7. Plant viscid; leaf blades involute
8
7. Plant not viscid; leaf blades flat or V-shaped
9
8. Floral scales 2.4-2.6 mm wide; achene obovate, 0.9-1 mm wide, black to dark brownish or reddish black, with a hyaline, iridiscent overlay
8. Floral scales 1.5-2.4 mm wide; achene oblanceolate, 0.5-0.8 mm wide, dull light to dark brown
9. Culm bases scarcely if at all cormose; basal leaf sheaths brown to dark purplish or dark red; floral scales reddish; rachilla wings 0.2 mm wide
9. Culm bases distinctly globose-cormose, the culm about half as wide as the cormose base; pale brown, pinkish red, to pale yellow or greenish; floral scales light brown, off-white, or stramineous; rachilla wingless or wings to 0.6 mm wide
10
10. Spikelet clusters usually sessile or subsessile, rarely a few pedunculate; rachilla wings absent; floral scales 2.6-3.6 mm long; achene sessile
10. Spikelet clusters (at least some) usually pedunculate; rachilla wings 0.4-0.6 mm wide; floral scales 2-2.8 mm long; achene substipitate
1. (Key G) Culms antrorsely scabrid; leaf blades and bracts with some distinct cross-veins
2
1. Culms smooth to mostly retrorsely scabrid; leaf blades and bracts lacking cross-veins
3
2. Primary inflorescence branches 3-5; floral scales ovate, 1.4-1.6 mm long; achenes 1-1.2 mm long
2. Primary inflorescence branches 6-12; floral scales oblanceolate, (1.3)1.5-2(2.4) mm long; achenes 1.2-1.5 mm long
3. Achene base swollen, spongy
3. Achene base not swollen, sometimes stipitate
4
4. Floral scale apex erecct to slightly recurved; achene linear, 0.2-0.3 mm wide, 4-5 times as long as wide
4. Floral scale apex mostly incurved; achene ovoid to ellipsoid, 0.2-0.7 mm wide, 2-3 times as long as wide
5
5. Longest inflorescence bract erect, continuous with the culm; floral scales pinkish or reddish
5. Longest inflorescence bract spreading to ascending, not continuous with the culm; floral scales yellowish to green
6
6. Culms smooth; achene 0.4-0.7 mm wide, usually stipitate
7
6. Culms smooth to retrorsely scabrid (rarely a prickle antrorse); achene 0.2-0.4 mm wide, not or scarcely stipitate
8
7. Inflorescence usually densely congested, the spikelet clusters mostly longer than to slightly shorter than their subtending peduncles; floral scales 2-2.3 mm long; achene surface puncticulate
7. Inflorescence open, the spikelet clusters mostly much shorter than their elongate subtending peduncles; floral scales (1.2)1.5-2 mm long; achene surface partly reticulate
8. Culm base dark reddish brown, dark purplish, to nearly black; floral scales (1.2)1.4-1.6(1.8) mm long, pale green
8. Culm base pale reddish or brownish green; floral scales 1-1.5 mm long, yellowish green
1. (Key H) Culms glabrous; leaves and bracts glabrous except for marginal prickles; spikes ca. 2 times long as wide; rachilla wing clasping achene for its entire length (therefore achene not visible in abaxial view); floral scales golden brown
1. Culms (at least distally) minutely to densely scabridulous; leaves and bracts harshly scabrid or hirtellous on adaxial surface; spikes nearly as wide as long; rachilla wing clasping achene 3/4 or less of its length; floral scales grayish green to brown, often red-purple striate
2
2. Culm obtusely trigonous to subterete; leaves and inflorescence bracts usually puberulent; inflorescence branches scabrid; spikes tight, burlike, turbinate; terminal scale spinose; spikelets with 1(–2) floral scales; rachilla wing hyaline, clasping achene ca. 1/2 its length; longest bract equaling or shorter than longest ray;
2. Culm sharply angled; leaves and inflorescence bracts with pubescence confined to midrib on abaxial side; inflorescence branches glabrous (rarely with a few antrorse hairs proximal to spike); spikes loose, obtrulloid to obdeltoid; terminal scale not spinose; spikelets with 3–6(8) floral scales; rachilla wing papery with narrow, hyaline border, clasping achene for 3/4 its length; longest ray shorter than bracts
1. (Key I) Culms, rays, and leaf blades papillose; leaves harshly scabrid on margins and midribs
1. Culms, rays, and leaf blades not papillose; leaves scabridulous or glabrous on margins and midribs
2
2. Spikelet clusters sessile, or most sessile and a few pedunculate; spikelets mostly ascending; floral scales 1.8-2.6 mm wide
2. Spikelet clusters with numerous pedunculate ones and few sessile ones (more sessile in C. blodgettii); spikelets mostly spreading, or distal ones ascending, middle ones spreading, and proximal ones descending; floral scales 1-2.2 mm wide
3
3. Floral scales 3.5-4.5 mm long
3. Floral scales 1.8-3.6 mm long
4
4. Spikelet clusters subglobose and about as long as wide; spikelets 4-8 mm long; floral scales 2.3-3.6 mm long, 1.8-2.2 mm wide
4. Spikelet clusters subcylindric and 1.2–3 times longer than wide; spikelets 4-7 mm long; floral scales 1.8-2.6 mm long, 1-1.5 mm wide
5
5. Spikelets 4-7 mm long, 1.5-2 mm wide; stigma 1-2 mm long; floral scales ascending (rarely subappressed); achenes oblong-fusiform; rachilla wing thin, deciduous, covering less than 1/2 achene face
6
5. Spikelets 2.2-4(4.5) mm long, 0.8-1.6 mm wide; stigma 0.6-0.9 mm long; floral scales appressed; achenes abruptly constricted, not fusiform; rachilla wing persistent, 0.2–0.3 mm wide, covering at least 1/2 achene face
7
6. Most spikelet clusters sessile, few pedunculate, peduncles <2 cm long; floral scales greenish to reddish brown
6. Most spikelet clusters pedunculate, few sessile, peduncles to 8 cm long
7. Inflorescence bracts usually divaricate; of xeric areas
7. Inflorescence bracts usually ascending; of mesic areas
1. (Key J) Inflorescence usually branched below spikelet clusters; spikelets ascending to erect, loosepaniculate, floral scales obovate-orbiculate, apex emarginate; styles <0.1 mm long
1. Inflorescence usually unbranched below spikelet clusters, occasionally branching; spikelets mostly spreading (sometimes some distal ones ascending to erect); floral scales elliptic, oblong, or ovate, apex acute to obtuse; styles 0.2–3.6 mm long
2
2. Floral scales 2-7 per spikelet
3
2. Floral scales (3)6-36(42) per spikelet
4
3. Leaf blades 3-10 mm wide; spikelets narrowly ellipsoid, 1.5–2 mm wide
3. Leaf blades 0.8-3 mm wide; spikelets oblong to linear, 0.6–1.6 mm wide
4. Rachis hispidulous
4. Rachis glabrous
3
5. Floral scales sparse along rachilla, the apex of the scale barely (if at all) reaching the base of the proceeding scale (along the same side of the rachilla)
5. Floral scales imbricate along the rachilla
6
6. Floral scales (2.1)2.4-4 times as long as wide
7
6. Floral scales 1-2 times as long as wide
8
7. Floral scales densely red-glandular punctate, mucronulate to mucronate, mucro 0.2–0.5 mm, terminal scale conduplicate; anthers 0.5–0.8(–1.4) mm; styles 0.8–1 mm; stigmas 1–2 mm
7. Floral scales eglandular, acute at the apex, terminal scale involute; anthers 0.3–0.5 mm; styles 1–2 mm; stigmas 3–4 mm
8. Floral scales whitish with a light green edge, and often reddish speckled
8. Floral scales mostly brown, red-brown, reddish, or greenish, not speckled
9
9. Plants without rhizomes, stolons, or tubers; floral scales 0.8-1.3 mm wide
10
9. Plants rhizomatous, stoloniferous, or tuberous; floral scales (1)1.4-3 mm wide
11
10. Plants perennial; culms 50–150 cm long, 2–15 mm wide; floral scales 1.6–1.8 mm long; achenes 0.9 mm long; anthers 0.4–0.5 mm long
10. Plants annual; culms 5-25(105) cm long, 1–2.5(8) mm wide; floral scales 1.3–1.5 mm long; achenes 0.4–0.6 mm long; anthers 0.2–0.3 mm long
11. Robust, rhizomatous, the culm base usually reddish brown; floral scales deciduous; achene coarsely punctate
11. Usually weak, stoloniferous, tuber-bearing, (if robust, then the culm base mostly yellowish or greenish); floral scales persistent; achene puncticulate
12
12. Floral scales yellowish brown to dark brown
12. Floral scales purple to reddish brown, with green midrib
Genus Synonyms
| Synonym | Full Citation | Basionym | Type |
|---|---|---|---|
| No synonyms found. | |||