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creeping spikerush, radical fiber optic spikerush, root spikerush

black-fruit spike-rush, black-fruit spikesedge

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

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

to 2 times wider than thick, 35–60(–70) cm × 0.5–1.3 mm, hard, usually with to 10 blunt ribs, at 20X often finely ridged and minutely granular.

Leaves

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

distal leaf sheaths brown to reddish.

Spikelets

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.

3–12 × 3–4 mm;

proximal scale amplexicaulous, 3.5–4 mm, midrib region very broad and fleshy, apex entire;

subproximal scale with a flower;

floral scales 30–40, 8–10 per mm of rachilla, orange-brown to stramineous, midrib region stramineous, broadly ovate, papery or sometimes membranous, 3–4 × 2 mm, apex entire, rounded.

Flowers

perianth bristles equaling achene;

anthers yellow to brown, 0.3–0.5 mm.

perianth bristles present, sometimes rudimentary, brown, length variable, obscurely retrorsely spinulose;

anthers brown, 1.7–2.2 mm.

Achenes

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.

subdeltoid in outline, sometimes broadly obpyriform, equilaterally trigonous, angles prominent, 0.9–1.2 × 0.7–1.1 mm, apex truncate.

Tubercles

brown, pyramidal, 0.15 × 0.15–0.2 mm.

sessile, depressed-pyramidal, often apiculate, as wide as achene, 0.3–0.5 × 0.7–1.1 mm.

Eleocharis radicans

Eleocharis melanocarpa

Phenology Fruiting spring–winter (Apr–Dec). Fruiting summer.
Habitat Stream alluvium, lake margins, meadows, seeps, bogs Fresh, oligotrophic, acid, sandy or peaty, often drying shores, ponds, ditches
Elevation 100–1400 Ariz., Calif., Fla., La., Mich., Okla., Tex., Va. 10–300 m (0–1000 ft)
Distribution
from FNA
HI; n Mexico; West Indies; Central America (El Salvador); South America (Argentina, Chile)
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from FNA
AL; FL; GA; IN; MA; MI; NC; NY; RI; SC; TX; VA
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Discussion

Eleocharis melanocarpa is reported from Rhode Island; I have not seen a voucher specimen.

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

Source FNA vol. 23, p. 112. FNA vol. 23, p. 89.
Parent taxa Cyperaceae > Eleocharis > subg. Scirpidium Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Melanocarpae
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. 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
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. 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. vivipara, E. wolfii
Synonyms Scirpus radicans, E. acicularis var. radicans, E. lindheimeri
Name authority (Poiret) Kunth: Enum. Pl. 2: 142. (1837) Torrey: Ann. Lyceum Nat. Hist. New York 3: 311. (1836)
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