Eleocharis parvula |
Eleocharis occulta |
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dwarf spikerush, dwarf spikesedge, little-head spike-rush, little-head spikesedge, small spike-rush, éléocharide naine |
limestone spike-rush |
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Habit | Plants perennial, densely cespitose; rhizomes concealed by persistent dead culm bases, often ascending, short, 3–5 mm thick, hard, cortex persistent, internodes very short, scales decaying to coarse fibers, 5–12 mm, papery. | |
Culms | subterete to slightly compressed, less than 2 times wider than thick, with 4–7 blunt ridges when dry, 27–56 cm × 0.2–0.5(–0.7) mm, firm to hard, spongy. |
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Leaves | distal leaf sheaths persistent, not splitting, proximally red, distally green to stramineous, often inflated, thinly papery to membranous, sometimes translucent, apex broadly obtuse to subtruncate, often callose, tooth absent. |
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Spikelets | 2–4 × 1–2 mm, sometimes absent in deeper water; proximal scale 1/2 or more of spikelet length; floral scales 6–10 per spikelet, 1.4–2.7 mm, commonly entirely stramineous, apex rounded to subacute. |
ovoid, 3–10 × 2–3 mm, apex acute; proximal scale amplexicaulous, apex 2-fid; subproximal scale with a flower; floral scales spreading in fruit, 20–50, 7 per mm of rachilla, medium brown, midrib region often narrowly stramineous, carinate, lanceolate-attenuate, 2–2.8 × 1 mm, apex 2-fid. |
Flowers | perianth bristles 6, stramineous, fairly stout to slender, usually equaling achene to slightly exceeding tubercle, sometimes unequal and some 1/2 of achene, very rarely rudimentary, minutely retrorsely spinulose; anthers 0.7–1.2 mm. |
perianth bristles 3 or absent, stramineous to pale brown, rudimentary to 1/2 achene length, obscurely retrorsely spinulose; stamens 3; anthers orange-brown, 0.7–1.3 mm; styles 3-fid. |
Achenes | stramineous, sometimes pale brown, obovoid to obpyriform, thickly trigonous, angles distinct, faces concave to plane, rarely convex, 0.9–1.2 × 0.55–0.75 mm, apex tapered, smooth or faintly rough at 30X. |
falling with scales, medium or dark brown, obpyriform, nearly equilaterally obscurely trigonous or cross section nearly circular, 0.7–1 × 0.5–0.65 mm, neck distinct or rarely absent, obscurely rugulose at 10–30X, 30 or more low, blunt horizontal ridges in vertical series. |
Tubers | terminating rhizomes usually markedly J- or horseshoe-shaped, body (apart from apical bud) oblong, 2–2.5(–5) × 0.5–1 mm; tubers among culm bases straight, narrowly fusiform, 4–5 mm. |
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Tubercles | 0.1–0.2 × 0.15 mm. |
brown, depressed-pyramidal, often rudimentary, 0.1–0.15 × 0.2 mm. |
2n | = 10 (Europe). |
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Eleocharis parvula |
Eleocharis occulta |
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Phenology | Fruiting summer–fall (north) or late winter–fall (far south). | Fruiting spring (Mar–May), sometimes summer (Jul). |
Habitat | Brackish or saline, mostly coastal tidal marshes, shores, mud flats, swamps, ponds, ditches | Seasonally wet, calcareous seeps, depressions, swales, rock crevises, rocky stream beds, stream banks, wet meadows, pond margins, often on limestone |
Elevation | 0–600 m (0–2000 ft) | 80–300 m (300–1000 ft) |
Distribution |
AL; AR; CA; CT; FL; GA; IL; IN; KS; LA; MA; MD; ME; MI; MO; MS; NC; NJ; NY; OH; OR; SC; VA; WA; BC; NB; NL; NS; QC; Mexico; Central America (Nicaragua); Eurasia
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OK; TX |
Discussion | Plants without well-developed bristles are otherwise typical Eleocharis parvula. S.-O. Strandhede and R. M. T. Dahlgren (1968) provided a detailed description from Scandinavia; the mostly curved tubers of North American plants are differently shaped than the ovoid, mostly nearly straight tubers illustrated by them. Eleocharis parvula is very uncommon inland. Plants lacking spikelets and having rather broad culms with evident aerenchyma (E. parvula forma spongiosa Fassett) that are submerged in tidal zones closely resemble small plants of Sagittaria graminea. Eleocharis parvula has also been reported from North Dakota, South America, and Africa; I have not seen specimens. Plants without achenes or tubers cannot be reliably identified to species. Literature reports from Cuba, Mexico, and Venezuela may be based on specimens of E. coloradoensis. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Eleocharis occulta is very invariable in contrast to the extreme variability of E. compressa. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 106. | FNA vol. 23, p. 83. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Parvulae | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Eleocharis |
Sibling taxa | ||
Synonyms | Scirpus parvulus, E. pygmaea, S. nanus | |
Name authority | (Roemer & Schultes) Link ex Bluff Nees: Comp. Fl. German. ed. 2, 1: 93. (1836) | S. G. Smith: Novon 11: 247, figs. 2, 3E–K. (2001) |
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