Eleocharis interstincta |
Eleocharis aestuum |
|
---|---|---|
knotted spikerush |
tidal spikerush, tidal spikesedge |
|
Habit | Plants perennial; rhizomes 2–4 mm thick, firm, longer internodes 3–7.5 cm, scales 5 mm, tubers absent. | |
Culms | terete, 45–100 cm × (3.2–)5–9.4 mm, soft to firm, sometimes septate-nodulose proximally, not distally, internally hollow with complete transverse septa, closer together near the spikelet, evident externally; plants never forming filiform, flaccid culms. |
often spreading or declining, 3–30 cm × 0.5–1 mm. |
Leaves | distal leaf sheaths persistent, membranous to thinly papery, apex acute to acuminate. |
apex of distal leaf sheath obtuse, tooth to 0.2(–0.5) mm. |
Spikelets | not proliferous, (20–)40–62 × 4–7 mm; rachilla joints bearing prominent wing-like remnants of floral scales; proximal scale empty, amplexicaulous, (3–)3.5–5 mm; floral scales 115–220, 1–3 per mm of rachilla, stramineous to pale brown, usually with pale to dark brown submarginal band, midrib region sometimes greenish, obovate to broadly oblong, (4–)4.5–5 × 2.8–4 mm, cartilaginous, often membranous toward margins, margins broadly translucent, membranous, apex rounded to subacute. |
ellipsoid to ovoid, 3–10 × 2–4 mm, apex blunt to subacute; floral scales 10–100+, 10 per mm of rachilla, colorless to pale brownish except for green midrib, 1.5–2 × 1 mm, midribs not keeled, apex rounded. |
Flowers | perianth bristles 6–8, stramineous, stout, flattened, subequal, exceeding achene, to 2.9 mm, coarsely spinulose; anthers stramineous to reddish, 2.5–5 mm; styles 2-fid or 3-fid. |
perianth bristles absent or 2–4, stramineous or whitish, shorter than to nearly 1/2 achene, very slender, without spinules; stamens 2(–3); anthers 0.3–0.5 mm; styles 2-fid or some 3-fid. |
Achenes | stramineous to golden-yellow or reddish brown or gray, obovoid to obpyriform, biconvex or nearly plano-convex, often with abaxial longitudinal ridge, 1.4–1.8(–2) × 1.1–1.4 mm, markedly sculptured at 10–15X, each face with 23–37 rows of transversely elongated cells, the longitudinal walls separating the cells often prominent, apex with short neck 0.7–0.8 mm wide. |
0.75–1 × 0.6–0.8 mm. |
Tubercles | dark brown, lamelliform, slightly higher than wide, 0.7–1.1 × 0.5–0.7 mm. |
deltoid, 0.2–0.3 × 0.35–0.45(–0.55) mm, 1/2–3/4as high as wide, 1/4–1/3 as high and 1/2–2/3(–4/5) as wide as achene. |
Eleocharis interstincta |
Eleocharis aestuum |
|
Phenology | Fruiting late spring–winter. | Fruiting summer–fall (Jul–Oct). |
Habitat | Fresh ponds, lakeshores, marshes, springs, ditches, canals | Fresh tidal river shores |
Elevation | 10–500 m (0–1600 ft) | 0–10 m (0–0 ft) |
Distribution |
FL; OK; TX; Mexico; Central America; e South America
|
CT; DE; MA; ME; NJ; NY; PA |
Discussion | Contrary to statements in the literature, sectioning reveals that the culm septa are closer together near the spikelet than in the rest of the culm in both Eleocharis interstincta and E. equisetoides. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Eleocharis aestuum is very similar to E. diandra and E. ovata; E. diandra differs from E. aestuum in its lower tubercles, brown floral scales, and absence of perianth bristles; E. ovata differs as given in the key to species. D. M. Hines (1975) described E. aestuum using the epithet “palidostachys” [ined.]. Specimens from shores of the Lake-of-the-Woods in Minnesota, and a reservoir and farm in Hardin and Fayette counties, Tennessee, may be referable to E. aestuum. The only recent records of E. aestuum are from the Androscoggin and Kennebec rivers in Maine and the Hudson River in New York (A. Haines 2001). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 119. | FNA vol. 23, p. 104. |
Parent taxa | Cyperaceae > Eleocharis > subg. Limnochloa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Ovatae |
Sibling taxa | ||
Synonyms | Scirpus interstinctus | |
Name authority | (Vahl) Roemer & Schultes: in J. J. Roemer et al., Syst. Veg. 2: 149. (1817) | Hines ex A. Haines: Novon 11: 45. (2001) |
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