Eleocharis radicans |
Eleocharis rostellata |
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creeping spikerush, radical fiber optic spikerush, root spikerush |
beak spike-rush, beak spikesedge, walking sedge, walking 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 densely tufted, mat-forming by means of rooting culm tips. |
Culms | obscurely to ca. 10-ribbed when dry, terete, 1–12 cm × 0.4–1 mm, very soft, spongy. |
1.5–3 times as wide as thick, 20–100 cm × 0.35–2 mm, firm to hard, wiry, with to 8 subacute ribs, rarely nearly smooth; some culms arching or decumbent and rooting at tips. |
Leaves | distal leaf sheaths fugaceous, colorless, translucent, apex blunt. |
distal leaf sheaths not splitting abaxially, proximally dark red to brown, apex usually 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. |
ovoid, 5–17 × 2.5–5 mm, apex acute; spikelets on stolons rudimentary, non-flowering, proliferous when rooting; proximal scale empty, amplexicaulous, ovate, 2–4 mm; subproximal scale with flower; floral scales 20–40, 2–3 per mm of rachilla, stramineous to medium brown, midrib region paler, ovate, 3.5–6 × 2–3 mm, membranous to cartilaginous, apex entire, rounded to subacute. |
Flowers | perianth bristles equaling achene; anthers yellow to brown, 0.3–0.5 mm. |
perianth bristles brown, equaling achene or tubercle, densely spinulose; anthers brown, 2–2.4 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. |
often very variable within one plant, ovoid to obovoid or obpyriform, 1.5–2.5 × 1–1.2 mm, beak to 1 × 0.6 mm. |
Tubercles | brown, pyramidal, 0.15 × 0.15–0.2 mm. |
when present pale to dark brown, pyramidal, to 0.5 × 0.3 mm. |
Eleocharis radicans |
Eleocharis rostellata |
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Phenology | Fruiting spring–winter (Apr–Dec). | Fruiting late spring in south, summer–fall in north. |
Habitat | Stream alluvium, lake margins, meadows, seeps, bogs | Very wet calcareous or brackish fens, springs, shores |
Elevation | 100–1400 Ariz., Calif., Fla., La., Mich., Okla., Tex., Va. | 50–2400 m (200–7900 ft) |
Distribution |
HI; n Mexico; West Indies; Central America (El Salvador); South America (Argentina, Chile)
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AZ; CA; CT; DE; FL; ID; IL; IN; KS; LA; MA; MD; ME; MI; MN; MT; NC; NE; NJ; NM; NV; NY; OH; OK; PA; RI; SC; SD; TX; UT; VA; WA; WI; WY; BC; NS; ON; Mexico; West Indies (Cuba, Haiti, Puerto Rico)
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Discussion | Eleocharis rostellata is highly competitive, often forming large monospecific colonies. The South American E. platypus C. B. Clarke is often treated as a synonym of E. rostellata. Eleocharis rostellata superfically closely resembles E. suksdorfiana in its culms, spikelets, and achenes, but differs in the absence of creeping rhizomes, presence of stoloniferous culms, absence of a flower in the proximal scale, and achene surface details. The collection of E. rostellata I have seen from Miami-Dade County, Florida, is from 1877. I have not seen vouchers for Archuleta County, Colorado, by H. D. Harrington (1954), or for the localities in Montana and South Carolina, which are based on the map in H. K. Svenson (1934). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 23, p. 112. | FNA vol. 23, p. 90. |
Parent taxa | Cyperaceae > Eleocharis > subg. Scirpidium | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Rostellatae |
Sibling taxa | ||
Synonyms | Scirpus radicans, E. acicularis var. radicans, E. lindheimeri | Scirpus rostellatus |
Name authority | (Poiret) Kunth: Enum. Pl. 2: 142. (1837) | (Torrey) Torrey: Fl. New York 2: 347. (1843) |
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