Eleocharis montevidensis |
Eleocharis radicans |
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Montevideo spike rush, sand spikerush |
creeping spikerush, radical fiber optic spikerush, root spikerush |
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Habit | Plants perennial, mat-forming; rhizomes evident, long, 0.7–2 mm thick, firm, cortex persistent, longer internodes 1–2 cm, scales often fugaceous, 6–8 mm, membranous, not fibrous. | Plants perennial, mat-forming; rhizomes 0.2–0.5 mm thick, longer internodes 5–10 mm, scales not evident. |
Culms | terete or cross section elliptic or rectangular, with 5–10 blunt ridges when dry, 25–50 cm × 0.5–1.2 mm, firm to hard, spongy. |
obscurely to ca. 10-ribbed when dry, terete, 1–12 cm × 0.4–1 mm, very soft, spongy. |
Leaves | distal leaf sheaths persistent, not splitting, mostly proximally dark red, distally red to brown or green, thinly papery, apex usually red-brown, often callose, subtruncate to obtuse, tooth usually present on some or all culms, to 0.9 mm. |
distal leaf sheaths fugaceous, colorless, translucent, apex blunt. |
Spikelets | usually ovoid or ellipsoid to subcylindric, rarely lanceoloid, 4–12 × (1.5–)2–3 mm, apex rounded to acute; proximal scale amplexicaulous or clasping over 3/4 of culm, entire; subproximal scale empty or with flower; floral scales appressed in fruit, 30–100, 6–10 per mm of rachilla, orange-brown, midrib regions often greenish, oblong to ovate, 1.5–2.5 × 1–1.5 mm, apex entire, broadly rounded, sometimes acute in distal part of spikelet, usually horizontally wrinkled and recurved, often carinate in distal part of spikelet. |
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(–7), stramineous to medium brown, stout, often unequal, much shorter than to equaling achene, rarely all rudimentary; stamens 3; anthers dark yellow to stramineous, 0.8–1.5 mm; styles 3-fid or some 2-fid. |
perianth bristles equaling achene; anthers yellow to brown, 0.3–0.5 mm. |
Achenes | falling with scales, dark brown, obovoid to obpyriform, compressed trigonous, angles evident to obscure, 0.7–1 × 0.65–0.8 mm, neck absent to sometimes long, finely rugulose at 10–30X, over 20 horizontal ridges in vertical series, and/or minutely cancellate at 20–30X. |
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 | brown to whitish, pyramidal, as high as wide or sometimes greatly depressed, (0.1–)0.25–0.3 × 0.2–0.3 mm. |
brown, pyramidal, 0.15 × 0.15–0.2 mm. |
2n | = 20. |
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Eleocharis montevidensis |
Eleocharis radicans |
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Phenology | Fruiting spring–fall. | Fruiting spring–winter (Apr–Dec). |
Habitat | Wet soil, fresh ponds, lakes, streams, springs, seeps, marshes, ditches, grasslands | Stream alluvium, lake margins, meadows, seeps, bogs |
Elevation | 0–2300 m (0–7500 ft) | 100–1400 Ariz., Calif., Fla., La., Mich., Okla., Tex., Va. |
Distribution |
AL; AZ; CA; FL; KS; LA; MS; NC; NM; OK; SC; TX; Mexico; South America
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HI; n Mexico; West Indies; Central America (El Salvador); South America (Argentina, Chile)
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Discussion | The name Eleocharis montana was long misapplied to E. montevidensis. The type of E. palmeri, recognized as a species (H. K. Svenson 1957), is indistinguishable from specimens of E. montevidensis. Eleocharis montevidensis is extremely variable; the broadly rounded, usually wrinkled and recurved floral scales are diagnostic. Achenes often fail to form. Eleocharis montevidensis is apparently closely related to E. parishii, in which the floral scales are less densely placed on the rachilla and acute to rounded, and the spikelets are narrowly lanceoloid to cylindric. In the absence of achenes and rhizomes, some specimens of E. montevidensis are easily mistaken for E. tricostata. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 23, p. 80. | FNA vol. 23, p. 112. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Eleocharis | Cyperaceae > Eleocharis > subg. Scirpidium |
Sibling taxa | ||
Synonyms | E. arenicola, E. montana subsp. montevidensis, E. palmeri | Scirpus radicans, E. acicularis var. radicans, E. lindheimeri |
Name authority | Kunth: Enum. Pl. 2: 144. (1837) | (Poiret) Kunth: Enum. Pl. 2: 142. (1837) |
Web links |