Eleocharis geniculata |
Eleocharis tortilis |
|
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bent spike-rush, Canada spikesedge, capitate spike-rush |
twisted spikerush |
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Habit | Plants tufted, without creeping rhizomes. | Plants perennial, forming dense clumps, not stoloniferous, rhizomatous. |
Rhizomes | usually present, caudexlike, ascending, 1 mm thick, hidden by crowded culms; internodes and scales not evident. |
|
Culms | to 45 cm × 0.2–1 mm. |
sometimes spirally twisted, usually minutely red-spotted at 30X, acutely triangular or sometimes elliptic, 15–70 cm × 0.3–0.5(–1) mm, soft (to firm), often minutely granular at 10X. |
Leaves | distal leaf sheaths persistent, firm, distally tightly sheathing, apex acute. |
distal leaf sheaths persistent, stramineous to green, often minutely red-spotted, membranous to papery, apex subacute to narrowly acute, often with toothlike callus. |
Spikelets | orbicular to ovoid, 1–9 × 1–4 mm, apex rounded to acute; proximal scale without flower, not amplexicaulous; floral scales to 125, 11–14 per mm of rachilla, tightly appressed, dark red-brown to stramineous, ovate to elliptic, 0.8–3 × 0.6–2(–2.3) mm, membranous to cartilaginous, apex rounded to acute. |
basal spikelets absent; never proliferous, ovoid to lanceoloid or ellipsoid, terete, 4–12 × 2–4 mm, apex acute; proximal scale empty, deciduous, clasping 1/2 of culm, similar to floral scales; subproximal scale often empty; floral scales spiraled, 10–25, 5–6 per mm of rachilla, pale orange-brown, midrib regions broadly pale green to colorless, broadly ovate, 2–2.5(–3.5) × 1.5–2 mm, central area and often flanks papery to cartilaginous or sometimes membranous, midrib evident, apex subacute (to rounded). |
Flowers | perianth bristles (0–)4–8, typically 7, red-brown, rarely whitish, vestigial to much exceeding tubercle, typically equaling achene, spinules few to dense; styles 2-fid. |
perianth bristles 4–6, bright brown, stout, equaling to slightly exceeding tubercle; spinules dense, retrorse, sharply acute; stamens 3; anthers 0.5–0.9 mm; styles 3-fid. |
Achenes | brown ripening to black, biconvex, orbicular to obpyriform, 0.5–1.1 × 0.3–0.7 mm, apex rarely constricted proximal to tubercle, very finely reticulate at 40X. |
medium brown or yellowish or greenish, obpyriform, obtusely (often obscurely) compressed trigonous, angles evident, 1.2–1.7(–2.4) × 0.9–1.2(–2.2) mm, apex constricted proximal to tubercle, coarsely cancellate at 10X, each face with 8–10 longitudinal rows of distinctly depressed, enlarged cells. |
Tubercles | stramineous to whitish, umbonate to subconic, 0.2–0.4 × 0.2–0.5 mm, apex rounded to acute. |
brown to greenish (or bone-white), pyramidal, trigonous or cross section plano-convex, 0.3–0.7(–1) × 0.3–0.6(–0.9) mm, distinctly shorter or narrower than achene, apex acute, often acuminate. |
2n | = 10. |
|
Eleocharis geniculata |
Eleocharis tortilis |
|
Phenology | Fruiting spring–winter (Mar–Dec). | Fruiting spring (in south)–fall. |
Habitat | Brackish creeks, canal banks, dune depressions, hammocks, irrigation ditches, lakeshores, lagoons, mangrove thickets, maritime mud flats, ditches, salt marshes | Wet soil, freshwater, acidic places, seeps, bogs, ditches |
Elevation | 0–1500 m (0–4900 ft) | 10–100 m (0–300 ft) |
Distribution |
AL; AZ; CA; FL; GA; IL; IN; LA; MI; MS; NE; NM; NV; OH; OK; PA; TX; ON; Mexico; Central America; South America; West Indies; Bermuda; Asia; Africa; Pacific Islands
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AL; AR; FL; GA; LA; MD; MS; NC; NJ; SC; TN; TX; VA
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Discussion | The name Eleocharis caribaea (Rottbøll) S. F. Blake is considered by most contemporary authorities to be misapplied (K. L. Wilson 1990). Eleocharis geniculata has been reported from South Carolina; I have not seen a voucher. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Eleocharis tortilis differs consistently from E. tuberculosa only in tubercle size. Most specimens of E. tortilis have culms that are sharply trigonous and no more than 0.5 mm wide. However, about two-thirds of the specimens of E. tortilis from Texas resemble E. tuberculosa in having culms that are elliptic or subelliptic in cross section and that sometimes reach 1 mm wide. Those elliptic-culmed plants may deserve taxonomic recognition. I have not seen voucher specimens for reports in the literature (H. K. Svenson 1937; M. L. Brown and R. G. Brown 1984) for Alabama (Mobile, 1800s), Delaware (1908), Maryland (1863–1878), and New York (Long Island, 1903). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 101. | FNA vol. 23, p. 92. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Maculosae | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Tenuissimae |
Sibling taxa | ||
Synonyms | Scirpus geniculatus, E. capitata, E. caribaea, E. dispar | Scirpus tortilis |
Name authority | (Linnaeus) Roemer & Schultes: in J. J. Roemer et al., Syst. Veg. 2: 150. (1817) | (Link) Schultes: Mant. 2: 92. (1824) |
Web links |