FNA: Eleocharis vivipara vs. Eleocharis radicans

	Eleocharis vivipara	Eleocharis radicans
	sprouting spike-rush, umbrella hairgrass, viviparous spike-rush	creeping spikerush, radical fiber optic spikerush, root spikerush
Habit	Plants perennial, short-rhizomatous, forming dense clumps, often entirely vegetative; rhizomes caudexlike, ascending, internodes and scales hidden by crowded culms and sheaths, 0.5 mm thick.	Plants perennial, mat-forming; rhizomes 0.2–0.5 mm thick, longer internodes 5–10 mm, scales not evident.
Culms	often arching, often sering as stolons, broadly elliptic, (4–)7–38(–45) cm × (0.1–)0.3–0.7 mm, soft to firm.	obscurely to ca. 10-ribbed when dry, terete, 1–12 cm × 0.4–1 mm, very soft, spongy.
Leaves	distal leaf sheaths persistent or disintegrating, yellowish to pale brown, sometimes mottled or wholly red-brown, membranaous to papery, apex acute to narrowly obtuse.	distal leaf sheaths fugaceous, colorless, translucent, apex blunt.
Spikelets	basal spikelets absent; usually proliferous, ovoid to ellipsoid to linear or terete, 3.3–9.6 × 1.2–2.3 mm, apex acute; proximal scale empty, persistent, amplexicaulous, similar to floral scales (usually slightly longer, midrib broadly green); subproximal scale with a flower; floral scales spiraled, 5–25, 4–8 per mm of rachilla, pale brown, usually spotted, streaked or mottled red-brown to purple, midribs green or green and red-brown, elliptic to obovate, 1.8–2.7 × 1–1.5 mm, membranous to chartaceous (papery), midrib evident to prominent, apex rounded to obtuse.	ovoid, 2–3 × 1–1.5 mm, apex acute; scales 5–15, 5–7 per mm of rachilla, colorless to stramineous, rarely slightly reddish, medially broadly greenish to colorless, faintly 3–5-veined, often ovate, membranous, fleshy; proximal scale 2–2.5 × 0.7 mm, other scales 1.5–2 × 0.7 mm, midrib obscure to slightly keeled, apex acute to rounded.
Flowers	perianth bristles 5–6, red-brown (proximally often white), shorter than to equaling tubercle, rarely longer, 0.9–1.3(–2) mm; spinules sparse, retrorse, sharply acute; stamens 3; anthers yellow, 0.8–1.8 mm; styles 3-fid.	perianth bristles equaling achene; anthers yellow to brown, 0.3–0.5 mm.
Achenes	gray or greenish, obovoid or obpyriform, trigonous, angles very prominent, 0.6–0.9 × 0.55–0.8 mm, apex constricted proximal to tubercle, finely honeycomb-reticulate at 10–20X, each face with 20 or more rows of evident enlarged cells.	brownish, angles plus longitudinal ridges ca. 7, narrowly obovoid, 2 times longer than wide, 0.75–0.9 × 0.35–0.4 mm, trabeculae ca. 50, distinct.
Tubercles	whitish, gray, brown, or greenish black, pyramidal, trigonous, 0.2–0.5 × 0.4–0.5 mm.	brown, pyramidal, 0.15 × 0.15–0.2 mm.

	Eleocharis vivipara	Eleocharis radicans
Phenology	Fruiting spring–fall.	Fruiting spring–winter (Apr–Dec).
Habitat	Sandy and peaty soils, ditches, pond margins, shallow waters bordering pine-flatwoods and pine-palmetto scrub	Stream alluvium, lake margins, meadows, seeps, bogs
Elevation	0–80 m (0–300 ft)	100–1400 Ariz., Calif., Fla., La., Mich., Okla., Tex., Va.
Distribution	AL; FL; GA; LA; NC; SC; VA [WildflowerSearch map] [BONAP county map]	HI; n Mexico; West Indies; Central America (El Salvador); South America (Argentina, Chile) [WildflowerSearch map] [BONAP county map]
Discussion	Most specimens of Eleocharis vivipara are from Florida. Identification of vegetative (often aquatic) specimens is sometimes tentative. Eleocharis vivipara is often confused with E. microcarpa and E. brittonii, and sometimes with E. baldwinii. The red-spotted band at the sheath apex and the gray, cancellate achenes are characteristic of E. vivipara. (Discussion copyrighted by Flora of North America; reprinted with permission.)
Source	FNA vol. 23, p. 93.	FNA vol. 23, p. 112.
Parent taxa	Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Tenuissimae	Cyperaceae > Eleocharis > subg. Scirpidium
Sibling taxa	E. acicularis, E. aestuum, E. albida, E. ambigens, E. atropurpurea, E. baldwinii, E. bella, E. bernardina, E. bicolor, E. bifida, E. bolanderi, E. brachycarpa, E. brittonii, E. cancellata, E. cellulosa, E. coloradoensis, E. compressa, E. cylindrica, E. decumbens, E. diandra, E. elliptica, E. elongata, E. engelmannii, E. equisetoides, E. erythropoda, E. fallax, E. flavescens, E. geniculata, E. intermedia, E. interstincta, E. kamtschatica, E. lanceolata, E. macrostachya, E. mamillata, E. melanocarpa, E. microcarpa, E. minima, E. montana, E. montevidensis, E. nana, E. nigrescens, E. nitida, E. obtusa, E. obtusetrigona, E. occulta, E. ovata, E. pachycarpa, E. palustris, E. parishii, E. parvula, E. quadrangulata, E. quinqueflora, E. radicans, E. ravenelii, E. retroflexa, E. reverchonii, E. robbinsii, E. rostellata, E. suksdorfiana, E. tenuis, E. torticulmis, E. tortilis, E. tricostata, E. tuberculosa, E. uniglumis, E. wolfii	E. acicularis, E. aestuum, E. albida, E. ambigens, E. atropurpurea, E. baldwinii, E. bella, E. bernardina, E. bicolor, E. bifida, E. bolanderi, E. brachycarpa, E. brittonii, E. cancellata, E. cellulosa, E. coloradoensis, E. compressa, E. cylindrica, E. decumbens, E. diandra, E. elliptica, E. elongata, E. engelmannii, E. equisetoides, E. erythropoda, E. fallax, E. flavescens, E. geniculata, E. intermedia, E. interstincta, E. kamtschatica, E. lanceolata, E. macrostachya, E. mamillata, E. melanocarpa, E. microcarpa, E. minima, E. montana, E. montevidensis, E. nana, E. nigrescens, E. nitida, E. obtusa, E. obtusetrigona, E. occulta, E. ovata, E. pachycarpa, E. palustris, E. parishii, E. parvula, E. quadrangulata, E. quinqueflora, E. ravenelii, E. retroflexa, E. reverchonii, E. robbinsii, E. rostellata, E. suksdorfiana, E. tenuis, E. torticulmis, E. tortilis, E. tricostata, E. tuberculosa, E. uniglumis, E. vivipara, E. wolfii
Synonyms	Chlorocharis vivipara, E. curtisii	Scirpus radicans, E. acicularis var. radicans, E. lindheimeri
Name authority	Link: Hort. Berol. 1: 283. (1827)	(Poiret) Kunth: Enum. Pl. 2: 142. (1837)
Web links	Local Web sites: LA Plants WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: CA Local Web sites: CalFlora, CalPhotos WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Eleocharis radicans

sprouting spike-rush, umbrella hairgrass, viviparous spike-rush

creeping spikerush, radical fiber optic spikerush, root spikerush

Habit

Plants perennial, short-rhizomatous, forming dense clumps, often entirely vegetative; rhizomes caudexlike, ascending, internodes and scales hidden by crowded culms and sheaths, 0.5 mm thick.

Plants perennial, mat-forming; rhizomes 0.2–0.5 mm thick, longer internodes 5–10 mm, scales not evident.

Culms

often arching, often sering as stolons, broadly elliptic, (4–)7–38(–45) cm × (0.1–)0.3–0.7 mm, soft to firm.

obscurely to ca. 10-ribbed when dry, terete, 1–12 cm × 0.4–1 mm, very soft, spongy.

Leaves

distal leaf sheaths persistent or disintegrating, yellowish to pale brown, sometimes mottled or wholly red-brown, membranaous to papery, apex acute to narrowly obtuse.

distal leaf sheaths fugaceous, colorless, translucent, apex blunt.

Spikelets

basal spikelets absent; usually proliferous, ovoid to ellipsoid to linear or terete, 3.3–9.6 × 1.2–2.3 mm, apex acute;

proximal scale empty, persistent, amplexicaulous, similar to floral scales (usually slightly longer, midrib broadly green);

subproximal scale with a flower;

floral scales spiraled, 5–25, 4–8 per mm of rachilla, pale brown, usually spotted, streaked or mottled red-brown to purple, midribs green or green and red-brown, elliptic to obovate, 1.8–2.7 × 1–1.5 mm, membranous to chartaceous (papery), midrib evident to prominent, apex rounded to obtuse.

ovoid, 2–3 × 1–1.5 mm, apex acute;

scales 5–15, 5–7 per mm of rachilla, colorless to stramineous, rarely slightly reddish, medially broadly greenish to colorless, faintly 3–5-veined, often ovate, membranous, fleshy;

proximal scale 2–2.5 × 0.7 mm, other scales 1.5–2 × 0.7 mm, midrib obscure to slightly keeled, apex acute to rounded.

Flowers

perianth bristles 5–6, red-brown (proximally often white), shorter than to equaling tubercle, rarely longer, 0.9–1.3(–2) mm;

spinules sparse, retrorse, sharply acute;

stamens 3;

anthers yellow, 0.8–1.8 mm;

styles 3-fid.

perianth bristles equaling achene;

anthers yellow to brown, 0.3–0.5 mm.

Achenes

gray or greenish, obovoid or obpyriform, trigonous, angles very prominent, 0.6–0.9 × 0.55–0.8 mm, apex constricted proximal to tubercle, finely honeycomb-reticulate at 10–20X, each face with 20 or more rows of evident enlarged cells.

brownish, angles plus longitudinal ridges ca. 7, narrowly obovoid, 2 times longer than wide, 0.75–0.9 × 0.35–0.4 mm, trabeculae ca. 50, distinct.

Tubercles

whitish, gray, brown, or greenish black, pyramidal, trigonous, 0.2–0.5 × 0.4–0.5 mm.

brown, pyramidal, 0.15 × 0.15–0.2 mm.

Eleocharis vivipara

Eleocharis radicans

Phenology

Fruiting spring–fall.

Fruiting spring–winter (Apr–Dec).

Habitat

Sandy and peaty soils, ditches, pond margins, shallow waters bordering pine-flatwoods and pine-palmetto scrub

Stream alluvium, lake margins, meadows, seeps, bogs

Elevation

0–80 m (0–300 ft)

100–1400 Ariz., Calif., Fla., La., Mich., Okla., Tex., Va.

Distribution

AL; FL; GA; LA; NC; SC; VA

[WildflowerSearch map]

[BONAP county map]

HI; n Mexico; West Indies; Central America (El Salvador); South America (Argentina, Chile)

[WildflowerSearch map]

[BONAP county map]

Discussion

Most specimens of Eleocharis vivipara are from Florida. Identification of vegetative (often aquatic) specimens is sometimes tentative. Eleocharis vivipara is often confused with E. microcarpa and E. brittonii, and sometimes with E. baldwinii. The red-spotted band at the sheath apex and the gray, cancellate achenes are characteristic of E. vivipara.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source

FNA vol. 23, p. 93.

FNA vol. 23, p. 112.

Parent taxa

Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Tenuissimae

Cyperaceae > Eleocharis > subg. Scirpidium

Sibling taxa

E. acicularis, E. aestuum, E. albida, E. ambigens, E. atropurpurea, E. baldwinii, E. bella, E. bernardina, E. bicolor, E. bifida, E. bolanderi, E. brachycarpa, E. brittonii, E. cancellata, E. cellulosa, E. coloradoensis, E. compressa, E. cylindrica, E. decumbens, E. diandra, E. elliptica, E. elongata, E. engelmannii, E. equisetoides, E. erythropoda, E. fallax, E. flavescens, E. geniculata, E. intermedia, E. interstincta, E. kamtschatica, E. lanceolata, E. macrostachya, E. mamillata, E. melanocarpa, E. microcarpa, E. minima, E. montana, E. montevidensis, E. nana, E. nigrescens, E. nitida, E. obtusa, E. obtusetrigona, E. occulta, E. ovata, E. pachycarpa, E. palustris, E. parishii, E. parvula, E. quadrangulata, E. quinqueflora, E. radicans, E. ravenelii, E. retroflexa, E. reverchonii, E. robbinsii, E. rostellata, E. suksdorfiana, E. tenuis, E. torticulmis, E. tortilis, E. tricostata, E. tuberculosa, E. uniglumis, E. wolfii

E. acicularis, E. aestuum, E. albida, E. ambigens, E. atropurpurea, E. baldwinii, E. bella, E. bernardina, E. bicolor, E. bifida, E. bolanderi, E. brachycarpa, E. brittonii, E. cancellata, E. cellulosa, E. coloradoensis, E. compressa, E. cylindrica, E. decumbens, E. diandra, E. elliptica, E. elongata, E. engelmannii, E. equisetoides, E. erythropoda, E. fallax, E. flavescens, E. geniculata, E. intermedia, E. interstincta, E. kamtschatica, E. lanceolata, E. macrostachya, E. mamillata, E. melanocarpa, E. microcarpa, E. minima, E. montana, E. montevidensis, E. nana, E. nigrescens, E. nitida, E. obtusa, E. obtusetrigona, E. occulta, E. ovata, E. pachycarpa, E. palustris, E. parishii, E. parvula, E. quadrangulata, E. quinqueflora, E. ravenelii, E. retroflexa, E. reverchonii, E. robbinsii, E. rostellata, E. suksdorfiana, E. tenuis, E. torticulmis, E. tortilis, E. tricostata, E. tuberculosa, E. uniglumis, E. vivipara, E. wolfii

Synonyms

Chlorocharis vivipara, E. curtisii

Scirpus radicans, E. acicularis var. radicans, E. lindheimeri

Name authority

Link: Hort. Berol. 1: 283. (1827)

(Poiret) Kunth: Enum. Pl. 2: 142. (1837)

Web links

Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).

Choose a data source: Flora of North America

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Eleocharis vivipara

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Eleocharis radicans