Eleocharis

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Contains 33 accepted taxa overall.

Family:CYPERACEAE
Genus: Eleocharis R.Br.
Common Name:SPIKERUSH
Specimen: View USF Herbarium specimens of this genus

Classification

Division
Class
Sub Class
Order POALES
FamilyCYPERACEAE
Genus Eleocharis

Citation

Citation ELEOCHARIS R. Brown, Prodr. 224. 1810.
Basionym: **
Type: TYPE: Eleocharis palustris (Linnaeus) Roemer & Schultes (Scirpus palustris Linnaeus) Lectotypified by Britton, Bull. Dept. Agric. Jamaica 5(suppl. 1): 10. 1907.

** Not applicable or data not available.

Species

Scientific NameCommon NameHerbarium SpecimensPhotos
Eleocharis acicularis NEEDLE SPIKERUSH
Eleocharis acutangula subsp. breviseta ACUTE SPIKERUSH
Eleocharis albida WHITE SPIKERUSH
Eleocharis atropurpurea PURPLE SPIKERUSH
Eleocharis baldwinii BALDWIN'S SPIKERUSH; ROADGRASS
Eleocharis cellulosa GULF COAST SPIKERUSH
Eleocharis confervoides ALGAL BULRUSH
Eleocharis elegans ELEGANT SPIKERUSH
Eleocharis elongata SLIM SPIKERUSH
Eleocharis equisetoides JOINTED SPIKERUSH
Eleocharis fallax CREEPING SPIKERUSH
Eleocharis flavescens YELLOW SPIKERUSH; PALE SPIKERUSH
Eleocharis geniculata CANADA SPIKERUSH
Eleocharis interstincta KNOTTED SPIKERUSH
Eleocharis melanocarpa BLACKFRUIT SPIKERUSH
Eleocharis microcarpa SMALLFRUIT SPIKERUSH
Eleocharis minima SMALL SPIKERUSH
Eleocharis montana MOUNTAIN SPIKERUSH
Eleocharis montevidensis SAND SPIKERUSH
Eleocharis mutata SCALLION GRASS
Eleocharis nana HAIRLIKE SPIKERUSH
Eleocharis nigrescens BLACK SPIKERUSH
Eleocharis obtusa BLUNT SPIKERUSH
Eleocharis olivacea BRIGHTGREEN SPIKERUSH
Eleocharis parvula DWARF SPIKERUSH
Eleocharis quadrangulata SQUARESTEM SPIKERUSH
Eleocharis radicans ROOTED SPIKERUSH
Eleocharis robbinsii ROBBINS' SPIKERUSH
Eleocharis rostellata BEAKED SPIKERUSH
Eleocharis tortilis TWISTED SPIKERUSH
Eleocharis tricostata THREE-ANGLE SPIKERUSH
Eleocharis tuberculosa CONECUP SPIKERUSH
Eleocharis vivipara VIVIPAROUS SPIKERUSH

Identification Key

1. Culms 0.5-9 mm wide, transverse septae conspicuous and complete or obscure and incomplete; spikelets (6)9-78 mm long, most 0.6-1.1 times as wide as the culm or 2-4 times as wideKey A
1. Culms 0.2-1 mm wide, transverse septae incomplete and obscure; spikelets 2-12(23) mm long, 2-8 times as wide as the culm2
2. Culms with branches in successive false whorls, which terminate in clusters of leaves essentially indistinguishable from stems, the spikelets borne singly on branches arising from among leaves; spikelets consisting of 2 scales, the single flower subtended by the distal scale (Websteria)E. confervoides
2. Culms unbranhced, with 1 terminal spikelets; spikelets with 4-160 scales and numerous flowers3
3. Styles 2-fid; achene biconvex or lenticular (Maculosae group)Key B
3. Styles 3-fid (or sometimes 2-fid in E. ambigens, E. minima, E. obtusa); achene trigonous to subterete or biconvexKey C
1. (Key A) Spikes often subulate, generally dark brown to reddish in color, with 100-500+ densely arranged floral scales, 15-40 scales per mm; floral scales 1-3 mm long, 1-1.5 mm wide, with 1 vein (rarely 10 widely spaced veins) (Truncatae group)2
1. Spikes mostly rounded, obutse, or abruptly acute at the tip, generally pale in color, with 4-220 floral scales, 0.5-3 scales per mm; floral scales 3-8 mm long, 2-5 mm wide, with 15+ obscure to prominent veins (subg. Limnochloa)3
2. Culms (2.8)3-6(10) mm wide, subequal to the spikelet width; achene tubercle 2-4 times longer than wide, nearly as long as the achene bodyE. elegans
2. Culms 0.5-3(4) mm wide, the spikelet 2-4 times wider than the culm; achene tubercle wider than or as wide as long, <1/2 as long as achene bodyE. montana
3. Culms 0.5-1.5 mm wide; spikelets 1.4–3 mm wide, with 4–26 floral scales; submersed culms sometimes flaccid and lacking spikelets4
3. Culms 2.5-9 mm wide; spikelets 3–8 mm wide, with 30–220 floral scales; submersed culms not becoming flaccid and sterile5
4. Floral scales 3.5-4.5 mm long, usually with a conspicuous brown to blackish submarginal band; achenes 0.6–1.3 mm long, 0.5–0.8 mm wide E. elongata
4. Floral scales 5-8 mm long, usually without a conspicuous submarginal band; achenes 1.9–2.6 mm long, 1–1.4 mm wideE. robbinsii
5. Culms distinctly septate (septae complete), internally hollow between septae6
5. Culms not septate or only obscurely so (septae incomplete), internally spongy7
6. Perianth bristles filiform, smooth to weakly toothed, shorter than to subequal to achene body; achene surface with linear-oblong cells medially and apically (rectangular towards the base)E. equisetoides
6. Perianth bristles flattened linear-lanceolate, coarsely retrorsely spinulose, longer than achene body; achene surface with rectangular cellsE. interstincta
7. Achene apex gradually narrowed and spongy-thickened, apex similar in texture (reticulate) to achene body except for the darkened tip (tubercle), tubercle scarcely differentiated and confluent, narrower than achene apex8
7. Achene apex constricted, sharply differentiated from the flared base of the tubercle9
8. Culm terete to scarcely trigonous; perianth bristles usually smooth; achene (including tubercle) 2.3-3.3 mm longE. cellulosa
8. Culm sharply 3-angled; perianth bristles retrorsely spinulose; achene (including tubercle) 1.8-2.2 mm longE. mutata
9. Culm 3-angled; perianth bristles usually retrorsely spinulose; achene 1.4-2 mm long, 1.2-1.6 mm wide, tubercle 0.3-0.8 mm longE. acutangula subsp. breviseta
9. Culm 4-angled; perianth bristles usually smooth to sparsely retrorsely spinulose; achene 1.8-3 mm long, 1.3-2 mm wide, tubercle 0.7-1.5 mm longE. quadrangulata
1. (Key B) Leaf sheath thin, delicate, hyaline, the margin sometimes tearing; achenes greenish to reddish or brown2
1. Leaf sheath firm, opaque, the margin intact; achenes black3
2. Achenes red-brown to dark brown, 0.4–0.8(1.1) mm long, 0.3–0.6 mm wide, apex usually not strongly constricted proximal to tubercle, perianth bristles usually shorter than to subequal to acheneE. flavescens
2. Achenes green to golden-brown, 0.5–1.1 mm long, 0.4–0.8 mm wide, usually strongly constricted proximal to tubercle, perianth bristles usually longer than the acheneE. olivacea
3. Perianth bristles colorless or white; achenes 0.3–0.5 mm long, 0.3–0.4 mm wide, apex often constricted to a neck below tubercle E. atropurpurea
3. Perianth bristles red-brown, rarely whitish; achenes 0.5–1.1 mm long, 0.3–0.7 mm wide, apex rounded below tubercleE. geniculata
1. (Key C) Achene surface with prominent longitudinal ribs, horizontal ridges much finer (Scirpidium group)2
1. Achene surface smooth, honeycomb-reticulate, finely reticulate, or cancellate, the ridges all fairly equal in prominence, lacking more strongly prominent longitidinal ribs3
2. Culms firm to flaccid, not very spongy, 1–45 cm long; anthers 0.5–1.5 mm longE. acicularis
2. Culms soft, very spongy, 1–12 cm long; anthers 0.3–0.5 mmE. radicans
3. Achenes apex gradually narrowed to a rudimentary or scarcely distinct tubercle, similar in texture and color to the achene body or only subtly changing4
3. Achenes apex generally narrowed below a distinct tubercle, the tubercle sharply differentiated from the achene body, the tubercle base usually flared6
4. Culms to 100 cm long, with 8 ridges; anthers 2-2.4 mm long; achene (including indistinct tubercle) 1.5-2.5 mm longE. rostellata
4. Culms to 55 cm long, with or without ridges; anthers 0.7-1.5 mm long; achene (including indistinct tubercle) 0.9-1.4 mm long5
5. Rhizomes with curved tubers; culms to 15(20) cm long, lacking ridges; perianth bristles 6E. parvula
5. Rhizomes lacking curved tubers; culms to 55 cm long, with 8-12 ridges; perianth bristles absentE. tricostata
6. Achenes 0.7-1.7 mm long; spikelets or culm tips not proliferous (or if proliferous, achene nearly black)7
6. Achenes 0.4-0.8(0.9) mm long, smooth, finely pitted, or cancellate; spikes or culm tips sometimes proliferous13
7. Achene coarsely honey-comb reticulate (Tuberculosae group)8
7. Achene smoothish to finely rugulose or cancellate9
8. Culm usually trigonous; tubercle much narrower and shorter than the achene, much smaller than the acheneE. tortilis
8. Culm terete; tubercle as long and as wide as achene, often larger than the acheneE. tuberculosa
9. Achenes dark purplish brown to black, smooth, widest near the apex, the tubercle 0.7-1.1 mm wide, as wide as the achene; some culms often arching or decumbent and with tips rootingE. melanocarpa
9. Achenes stramineous, orangish, to brown, widest near the middle, the tubercle 0.2-0.6 mm wide and usually narrower than the achene; culms not rooting at tips10
10. Achenes (0.9)1-1.5 mm long, (0.7)0.8-1.3 mm wide, the tubercle 0.3-0.5 mm long, 0.4-0.8 mm wide11
10. Achenes 0.7-1 mm long, 0.6-0.8 mm wide, the tubercle 0.1-0.3 mm long, 0.2-0.4 mm wide12
11. Spikelets 2-3 mm wide, acute at the tip, floral scales 3-5 per mmE. ambigens
11. Spikelets (2)3-4 mm wide, obtuse or rounded at the tip; floral scales 8-20 per mm (Ovatae group)E. obtusa
12. Culm base pale brownish (scarcely any red color if at all); leaf sheath apex acute to lanceolate or disintegrating; perianth bristles sometimes exceeding the tubercleE. albida
12. Culm base distinctly reddish; leaf sheath apex subtruncate to obtuse; perianth bristles not exceeding the tubercleE. montevidensis
13. Scales distichous; spikes with 2-4 flowersE. baldwinii
13. Scales spirally arranged (or spirodistichous); spike mostly with 4-50(75) flowers14
14. Achenes 0.45–0.9 mm, finely reticulate or cancellateE. vivipara
14. Achene smooth or very finely pitted15
15. Stolons and rhizomes absent; floral scales 1–1.2 mm long; perianth bristles absent; spikelets not proliferatingE. nigrescens
15. Stolons or rhizomes present; floral scales 1.3–2.2 mm long; perianth bristles present or absent; spikelets sometimes proliferating16
16. Spikelet proximal scale deciduous or sometimes persistent, similar to floral scales or smaller; perianth bristles present17
16. Spikelet proximal scale persistent, differentiated from floral scales, usually longer and resembling involucral bract, often with excurrent midrib; perianth bristles present or absent18
17. Rhizomes absent, stolons present; spikelets often proliferating; perianth bristles colorless to stramineous, slightly shorter than to equaling tubercle; achenes sometimes spotted olive or brownE. minima
17. Rhizomes present; spikelets not proliferating; perianth bristles red-brown, equaling to exceeding tubercle; achenes not spottedE. nana
18. Proximal scale apex rounded19
18. Proximal scale apex subacute to acute20
19. Plants usually robust; floral scales pale brown and papery; perianth bristles well developed; achenes to 0.8 mm long, minutely pittedE. brittonii
19. Plants usually small; floral scales whitish with red-brown markings; perianth bristles absent or poorly developed; achenes not more than 0.6 mm long, smoothE. brittonii variant
20. Spikelet proximal scale 0.8–1 mm wide; perianth bristles 0.6–1 mm longE. microcarpa var. filiculmis
20. Spikelet proximal scale 0.4–0.5 mm wide; perianth bristles 0.2–0.4 mm longE. microcarpa var. microcarpa

Genus Synonyms

SynonymFull CitationBasionymType
Bulbostylis Bulbostylis Steven, Mem. Soc. Imp. Naturalistes Moscou 5: 355. 1817, nom. rej. vs. Bulbostylis Kunth 1837. TYPE: Non designatus.
Chaetocyperus Chaetocyperus Nees von Esenbeck, Linnaea 9: 289. 1834. TYPE: Chaetocyperus setaceus (Retzius) Nees von Esenbeck (Cyperus setaceus Retzius) Lectotypified by Pfeiffer, Nomencl. Bot. 1: 684. 1873.
Clavula Clavula Dumortier, Fl. Belg. 143. 1827. TYPE: Non designatus.
Eleogenus Eleogenus Nees von Esenbeck, Linnaea 9: 294. 1834. TYPE: Non designatus.
Limnochloa Limnochloa Palisot de Beauvois ex Lestiboudois f., Essai Cyper. 41. 1819. TYPE: Non designatus.
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