Eleocharis radicans |
Eleocharis tortilis |
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creeping spikerush, radical fiber optic spikerush, root spikerush |
twisted spikerush |
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Habit | Plants perennial, mat-forming; rhizomes 0.2–0.5 mm thick, longer internodes 5–10 mm, scales not evident. | Plants perennial, forming dense clumps, not stoloniferous, rhizomatous. |
Rhizomes | usually present, caudexlike, ascending, 1 mm thick, hidden by crowded culms; internodes and scales not evident. |
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Culms | obscurely to ca. 10-ribbed when dry, terete, 1–12 cm × 0.4–1 mm, very soft, spongy. |
sometimes spirally twisted, usually minutely red-spotted at 30X, acutely triangular or sometimes elliptic, 15–70 cm × 0.3–0.5(–1) mm, soft (to firm), often minutely granular at 10X. |
Leaves | distal leaf sheaths fugaceous, colorless, translucent, apex blunt. |
distal leaf sheaths persistent, stramineous to green, often minutely red-spotted, membranous to papery, apex subacute to narrowly acute, often with toothlike callus. |
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. |
basal spikelets absent; never proliferous, ovoid to lanceoloid or ellipsoid, terete, 4–12 × 2–4 mm, apex acute; proximal scale empty, deciduous, clasping 1/2 of culm, similar to floral scales; subproximal scale often empty; floral scales spiraled, 10–25, 5–6 per mm of rachilla, pale orange-brown, midrib regions broadly pale green to colorless, broadly ovate, 2–2.5(–3.5) × 1.5–2 mm, central area and often flanks papery to cartilaginous or sometimes membranous, midrib evident, apex subacute (to rounded). |
Flowers | perianth bristles equaling achene; anthers yellow to brown, 0.3–0.5 mm. |
perianth bristles 4–6, bright brown, stout, equaling to slightly exceeding tubercle; spinules dense, retrorse, sharply acute; stamens 3; anthers 0.5–0.9 mm; styles 3-fid. |
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. |
medium brown or yellowish or greenish, obpyriform, obtusely (often obscurely) compressed trigonous, angles evident, 1.2–1.7(–2.4) × 0.9–1.2(–2.2) mm, apex constricted proximal to tubercle, coarsely cancellate at 10X, each face with 8–10 longitudinal rows of distinctly depressed, enlarged cells. |
Tubercles | brown, pyramidal, 0.15 × 0.15–0.2 mm. |
brown to greenish (or bone-white), pyramidal, trigonous or cross section plano-convex, 0.3–0.7(–1) × 0.3–0.6(–0.9) mm, distinctly shorter or narrower than achene, apex acute, often acuminate. |
Eleocharis radicans |
Eleocharis tortilis |
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Phenology | Fruiting spring–winter (Apr–Dec). | Fruiting spring (in south)–fall. |
Habitat | Stream alluvium, lake margins, meadows, seeps, bogs | Wet soil, freshwater, acidic places, seeps, bogs, ditches |
Elevation | 100–1400 Ariz., Calif., Fla., La., Mich., Okla., Tex., Va. | 10–100 m (0–300 ft) |
Distribution |
HI; n Mexico; West Indies; Central America (El Salvador); South America (Argentina, Chile)
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AL; AR; FL; GA; LA; MD; MS; NC; NJ; SC; TN; TX; VA
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Discussion | Eleocharis tortilis differs consistently from E. tuberculosa only in tubercle size. Most specimens of E. tortilis have culms that are sharply trigonous and no more than 0.5 mm wide. However, about two-thirds of the specimens of E. tortilis from Texas resemble E. tuberculosa in having culms that are elliptic or subelliptic in cross section and that sometimes reach 1 mm wide. Those elliptic-culmed plants may deserve taxonomic recognition. I have not seen voucher specimens for reports in the literature (H. K. Svenson 1937; M. L. Brown and R. G. Brown 1984) for Alabama (Mobile, 1800s), Delaware (1908), Maryland (1863–1878), and New York (Long Island, 1903). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 23, p. 112. | FNA vol. 23, p. 92. |
Parent taxa | Cyperaceae > Eleocharis > subg. Scirpidium | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Tenuissimae |
Sibling taxa | ||
Synonyms | Scirpus radicans, E. acicularis var. radicans, E. lindheimeri | Scirpus tortilis |
Name authority | (Poiret) Kunth: Enum. Pl. 2: 142. (1837) | (Link) Schultes: Mant. 2: 92. (1824) |
Web links |