Eleocharis equisetoides |
Eleocharis elongata |
|
---|---|---|
horsetail spike-rush, horsetail spikesedge, jointed spike-rush, jointed spike-rush (spikesedge), jointed spikesedge, knotted spike-rush |
slim spikerush |
|
Habit | Plants perennial; rhizomes 2–4 mm thick, soft to firm, longer internodes 2–8 cm, scales persistent, 7–8 mm, membranous, tubers absent. | Plants perennial; rhizomes 1–1.5 mm thick, soft, longer internodes 2–3 cm, scales 5–14 mm, tubers absent. |
Culms | terete, 50–100 cm × 5–8.4 mm, soft to firm, obscurely to clearly septate-nodulose throughout, internally hollow with complete transverse septa, closer together near the spikelet; plants never forming filiform, flaccid 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. |
Leaves | distal leaf sheaths persistent, membranous to thinly papery, apex acute to slightly acuminate. |
distal leaf sheaths persistent or decaying, membranous, apex acute, often prolonged into translucent portion to 1 mm. |
Spikelets | not proliferous, 20–45 × 4–5(–8) mm; rachilla joints bearing prominent winglike remnants of floral scales; proximal scale empty, amplexicaulous, (2–)2.8–4.9 mm; floral scales 85–160, 1–3 per mm of rachilla, stramineous to pale brown, usually with pale to dark brown submarginal band, obovate to oblong, (4.8–)5.2–7 × 3–4.4 mm, cartilaginous, often membranous toward margins, margins broadly translucent, membranous, apex rounded to obtuse. |
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 3–8, stramineous to reddish, slender, vestigial to 2.5 mm, shorter than to equaling achene, smooth or obscurely retrorsely spinulose; anthers stramineous to red-striated, 2.6–3.2 mm; styles 2–3-fid. |
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 | yellowish to reddish brown, obovoid, biconvex to obscurely compressed trigonous, 1.8–2.3 × 1.4–1.9 mm, obscurely sculptured or sometimes partially smooth at 10–15X, each face with 20–40 rows of linear, transversely elongated cells, lines separating cells obscure, apex with very short neck 0.6–0.8 mm wide. |
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. |
Tubercles | dark brown, lamelliform, high-deltoid, 0.6–1.1 × 0.5–0.7 mm. |
dark brown, pyramidal, 0.2–0.5 × 0.2–0.4 mm. |
Eleocharis equisetoides |
Eleocharis elongata |
|
Phenology | Fruiting late spring–late fall. | Fruiting late spring–late fall. |
Habitat | Fresh ponds, lakes, marshes, streams, ditches, cypress swamps | Sometimes drying ponds, lakeshores, marshes, creeks, canals, ditches |
Elevation | 10–500 m (0–1600 ft) | 10–50 m (0–200 ft) |
Distribution |
AL; CA; CT; FL; GA; IN; LA; MA; MD; MI; MO; MS; NC; NY; RI; SC; TX; VA; WI; ON
|
AL; FL; NC; TX; Mexico; Central America; South America |
Discussion | We have not seen voucher specimens for reports of Eleocharis equistoides from Arkansas and Tennessee. It is probably extirpated from Illinois, Missouri, and Wisconsin. Contrary to previous decriptions, sectioning of the culm reveals that the distance between the septa near the spikelet cannot be used to distinguish the two septate species, E. equisetoides and E. interstincta, which when achenes are absent are better distinguished by the septate-nodulose distal parts of the culms of E. equisetiodes. (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. | FNA vol. 23, p. 117. |
Parent taxa | Cyperaceae > Eleocharis > subg. Limnochloa | Cyperaceae > Eleocharis > subg. Limnochloa |
Sibling taxa | ||
Synonyms | Scirpus equisetoides, E. elliottii | |
Name authority | (Elliott) Torrey: Ann. Lyceum Nat. Hist. New York 3: 296. (1836) | Chapman: Fl. South. U.S., 515. (1860) |
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