Eleocharis parvula |
Eleocharis bifida |
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dwarf spikerush, dwarf spikesedge, little-head spike-rush, little-head spikesedge, small spike-rush, éléocharide naine |
glades spikerush |
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Habit | Plants perennial, densely cespitose; rhizomes concealed by persistent culm bases, short, 4–5 mm thick, hard, cortex persistent, internodes crowded, scales decaying to coarse fibers, 1 cm, papery. | |
Culms | greatly compressed, 4–10 times wider than thick, often with 1 or 2 sharp ridges on 1 side, (8–)20–35 cm × 0.7–2.3 mm, hard, finely striate, spongy. |
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Leaves | distal leaf sheaths persistent, not splitting, proximally red or stramineous, distally green to stramineous, inflated, papery, apex dark brown, broadly obtuse to subtruncate, 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, 4–9 × 2.5–4 mm, apex acute; proximal scale clasping 2/3–3/4 of culm, apex 2-fid; subproximal scale empty or with a flower; floral scales spreading in fruit, 30–60, 6–9 per mm of rachilla, medium or pale brown, midrib region often paler, ovate-lanceolate, 2.5–3.5 × 1.5 mm, apex 2-fid, carinate in distal part of spikelet. |
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 0(–5), stramineous to pale brown, 1/2 of to equaling achene length; stamens 3; anthers orange-brown, 0.7–1.5 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, yellow-brown to medium brown, obovoid to obpyriform, nearly equilaterally trigonous, cross section circular to slightly compressed, angles obscure or evident, 0.9–1.1 × 0.6–0.75, neck usually very short, finely rugulose at 10–30X, 20 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, 0.1–0.25 × 0.2–0.3 mm. |
2n | = 10 (Europe). |
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Eleocharis parvula |
Eleocharis bifida |
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Phenology | Fruiting summer–fall (north) or late winter–fall (far south). | Fruiting spring–summer (May–Jun). |
Habitat | Brackish or saline, mostly coastal tidal marshes, shores, mud flats, swamps, ponds, ditches | Seasonally wet places on limestone, cedar (juniper) glades, stream beds, prairies, ditches |
Elevation | 0–600 m (0–2000 ft) | 200–300 m (700–1000 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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AL; GA; KY; TN |
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 bifida was previously included in E. compressa. A very few specimens of E. compressa var. compressa from the states where E. bifida is known are like E. bifida except for their entire proximal floral scales and evident rhizomes. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 106. | FNA vol. 23, p. 85. |
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: 243, figs. 1F–J, 2. (2001) |
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