Eleocharis geniculata |
Eleocharis ambigens |
|
---|---|---|
bent spike-rush, Canada spikesedge, capitate spike-rush |
ambiguous spikesedge, éléocharide ambiquë |
|
Habit | Plants tufted, without creeping rhizomes. | Plants perennial, mat-forming; rhizomes evident, long, 1–2 mm thick, firm, cortex persistent, longer internodes 1–3 cm, scales persistent, 5–10 mm, membranous, not fibrous. |
Culms | to 45 cm × 0.2–1 mm. |
terete, often with to 16 blunt ridges when dry, 25–80 cm × 0.5–1.5 mm, firm, internally spongy. |
Leaves | distal leaf sheaths persistent, firm, distally tightly sheathing, apex acute. |
distal leaf sheaths persistent, not splitting, proximally dark red, distally red to stramineous or green, often callose, thinly papery (to membranous), apex dark red-brown, obtuse to subtruncate, tooth sometimes present on some culms, to 0.3 mm. |
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. |
ovoid to lanceoloid, 5–23 × 2–3(–4) mm, apex acute (to obtuse); proximal scale amplexicaulous, entire; subproximal scale with flower; floral scales often spreading in fruit, 10–60, 3–4 per mm of rachilla, medium brown, rarely red-brown, midrib regions mostly stramineous to green, in proximal part of spikelet ovate, in distal part lanceolate, 2.5–3.5 × 1.7 mm, entire, apex acute to rarely obtuse, often carinate in distal part of spikelet. |
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 2–4(–5), brown, slender to stout, usually very unequal, rudimentary to equaling achene; stamens 3; anthers brown, 1.5–2 mm; styles 2-fid, sometimes some 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. |
not persistent, dark yellow or stramineous, obovoid to obpyriform, all biconvex or some (very rarely all) compressedtrigonous, angles obscure, 1–1.5 × 0.9–1.25 mm, apex rounded, neck absent (to very short), finely rugulose at 10–20X, with 20 or more horizontal ridges in vertical series and/or finely cancellate at 10–30X. |
Tubercles | stramineous to whitish, umbonate to subconic, 0.2–0.4 × 0.2–0.5 mm, apex rounded to acute. |
brown or proximally whitish, pyramidal, depressed, rarely some as high as wide, 0.15–0.3(–0.5) × (0.3–)0.4–0.6 mm. |
2n | = 10. |
= 44, 45, 46. |
Eleocharis geniculata |
Eleocharis ambigens |
|
Phenology | Fruiting spring–winter (Mar–Dec). | Fruiting spring–summer. |
Habitat | Brackish creeks, canal banks, dune depressions, hammocks, irrigation ditches, lakeshores, lagoons, mangrove thickets, maritime mud flats, ditches, salt marshes | Coastal (rarely inland) fresh to brackish pond shores, marshes, disturbed places |
Elevation | 0–1500 m (0–4900 ft) | 0–10 m (0–0 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
|
CT; FL; GA; LA; MA; MS; NC; NJ; RI; SC; TX; VA; QC |
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 ambigens is usually treated as a synonym of E. fallax because some specimens from Massachusetts to Georgia have some 3-fid styles and some obscurely trigonous achenes. A specimen of E. ambigens from Louisiana has trigonous achenes. Eleocharis ambigens is very similar to and perhaps better included in E. uniglumis (S.-O. Strandhede 1967). Intermediates with E. macrostachya occur in Louisiana and Texas. The depressed tubercles are diagnostic of E. ambigens. Eleocharis ambigens is sometimes confused with E. montevidensis, which is readily distinguished by its floral scales with broadly rounded apices. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 101. | FNA vol. 23, p. 78. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Maculosae | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Eleocharis |
Sibling taxa | ||
Synonyms | Scirpus geniculatus, E. capitata, E. caribaea, E. dispar | |
Name authority | (Linnaeus) Roemer & Schultes: in J. J. Roemer et al., Syst. Veg. 2: 150. (1817) | Fernald: Rhodora 37: 394. (1935) |
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