Eleocharis radicans |
Eleocharis tuberculosa |
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creeping spikerush, radical fiber optic spikerush, root spikerush |
cone-cup spikerush, long-tubercled spikerush, long-tubercled spikesedge |
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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. |
Rhizomes | present or not, caudexlike, ascending, 1 mm thick; internodes and scales hidden by crowded culms, 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. |
elliptic or sometimes circular, with several rounded ridges and sulcate when dry, 15–75 cm × 0.3(–1.5) mm, firm, minutely granular at 10X. |
Leaves | distal leaf sheaths fugaceous, colorless, translucent, apex blunt. |
distal leaf sheaths persistent; stramineous to green, often minutely red-spotted, papery to membranous, apex subacute to narrowly acute, often with tooth-like 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, terete, 5–15 × 2.5–4 mm, apex acute; proximal scale empty, deciduous, clasping 1/2 of culm, similar to floral scales; subproximal scale often empty; floral scales spiraled, 10–30, 5–6 per mm of rachilla, pale orange-brown, midribs green, broadly ovate, 2.5–4 × 1.5–2.5 mm, central area and often flanks papery to cartilaginous (or membranous), midrib evident, apex broadly rounded to obtuse. |
Flowers | perianth bristles equaling achene; anthers yellow to brown, 0.3–0.5 mm. |
perianth bristles 5–6, bright brown, stout, slightly shorter than to equaling tubercle; spinules rarely absent, dense, variably from divaricate to antrorse, very short, and blunt to acute, to often much longer and retrorse, sharply acute; stamens 2–3; anthers 0.5–1 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, obovoid to obpyriform, compressed (often obscurely) trigonous, angles evident, 0.9–1.7 × 0.8–2 mm; apex often constricted proximal to tubercle, very coarsely cancellate at 10X, each face with 8–10 longitudinal rows of large depressions. |
Tubercles | brown, pyramidal, 0.15 × 0.15–0.2 mm. |
bone-white to pale orange-brown, often red-spotted, subpyramidal, cross section plano-convex, 0.9–1.7(–2.4) × 0.7–1.2–2(–2.2) mm, at least as high and wide as achene, spongy, apex rounded, often with an abaxial acute projection. |
Eleocharis radicans |
Eleocharis tuberculosa |
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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, ponds, lakeshores, streams, meadows, pine woods, grasslands, disturbed places, bogs |
Elevation | 100–1400 Ariz., Calif., Fla., La., Mich., Okla., Tex., Va. | 0–500 m (0–1600 ft) |
Distribution |
HI; n Mexico; West Indies; Central America (El Salvador); South America (Argentina, Chile)
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AL; AR; FL; GA; LA; MA; MS; NC; NJ; SC; TN; TX; NS
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Discussion | Eleocharis tuberculosa evidently is closely related to E. tortilis, from which it differs in its larger tubercles, culms that are always elliptic in cross section, and perianth bristle spinules that are often divaricate to antrorse and often blunt. The specimens of E. tuberculosa from throughout its range which are like E. tortilis in having retrorsely spinulose perianth bristles have been named E. tuberculosa forma retrorsa Svenson (type from Massachusetts). Plants from Nova Scotia with nearly smooth bristles have been named E. tuberculosa var. pubnicoensis Fernald and E. tuberculosa forma pubnicoensis (Fernald) Svenson. We have not seen voucher specimens for literature reports of Eleocharis tuberculosa from Connecticut, Delaware, Maine, Maryland, New Hampshire, New York, Pennsylvania, Rhode Island, or Virginia. (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 tuberculosus, E. tuberculosa var. pubnicoensis |
Name authority | (Poiret) Kunth: Enum. Pl. 2: 142. (1837) | (Michaux) Roemer & Schultes: in J. J. Roemer et al., Syst. Veg. 2: 152. (1817) |
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