Eleocharis parvula |
Eleocharis elongata |
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dwarf spikerush, dwarf spikesedge, little-head spike-rush, little-head spikesedge, small spike-rush, éléocharide naine |
slim spikerush |
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Habit | Plants perennial; rhizomes 1–1.5 mm thick, soft, longer internodes 2–3 cm, scales 5–14 mm, tubers absent. | |
Culms | obscurely trigonous to terete; spikelet-bearing culms 16–80 cm × 0.5–1.5 mm; when submersed plants often forming numerous, filiform flaccid culms without spikelets, sometimes with whorls of slender branches, 0.1–0.3 mm wide, soft; sometimes septate-nodulose when aquatic, internally spongy, transverse septa incomplete. |
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Leaves | distal leaf sheaths persistent or decaying, membranous, apex acute, often prolonged into translucent portion to 1 mm. |
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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. |
not proliferous, (6–)9–24 × 1.4–2.2 mm; rachilla joints bearing prominent winglike remnants of floral scales; proximal scale with a flower, amplexicaulous, 2.5–4.1 mm; floral scales 7–26, 1–2 per mm of rachilla, green to stramineous or pale brown, often minutely dotted reddish, usually with conspicuous dark brown to blackish submarginal band, narrowly ovate, 3.5–4.5 × 2 mm, thickly papery, membranous toward margins. |
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 6–7, whitish to stramineous or pale reddish brown, proximally slightly flattened, unequal, exceeding or rarely shorter than achene, 0.7–1.9 mm, retrorsely spinulose; anthers yellow to reddish, 1.7–1.9 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. |
whitish, stramineous, or pale green, obovoid to obpyriform, compressed trigonous with adaxial face broadest, or biconvex, 0.65–1.4 × 0.5–0.8 mm, clearly sculptured at 10–15X, each face with 10–13 rows of rectangular, transversely elongated cells, apex constricted to short neck 0.2–0.25(–0.3) mm wide, wider at tubercle base. |
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. |
dark brown, pyramidal, 0.2–0.5 × 0.2–0.4 mm. |
2n | = 10 (Europe). |
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Eleocharis parvula |
Eleocharis elongata |
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Phenology | Fruiting summer–fall (north) or late winter–fall (far south). | Fruiting late spring–late fall. |
Habitat | Brackish or saline, mostly coastal tidal marshes, shores, mud flats, swamps, ponds, ditches | Sometimes drying ponds, lakeshores, marshes, creeks, canals, ditches |
Elevation | 0–600 m (0–2000 ft) | 10–50 m (0–200 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; FL; NC; TX; Mexico; Central America; South America |
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 elongata sometimes grows with E. robbinsii; no intermediates are known. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 106. | FNA vol. 23, p. 117. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Parvulae | Cyperaceae > Eleocharis > subg. Limnochloa |
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) | Chapman: Fl. South. U.S., 515. (1860) |
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