Eleocharis geniculata |
Eleocharis brittonii |
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bent spike-rush, Canada spikesedge, capitate spike-rush |
Britton's spike-rush |
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Habit | Plants tufted, without creeping rhizomes. | Plants usually annual, tufted, often stoloniferous; rhizomes absent. |
Culms | to 45 cm × 0.2–1 mm. |
ascending, quadrangular, sulcate (not sulcate in Eleocharis sp. |
Leaves | distal leaf sheaths persistent, firm, distally tightly sheathing, apex acute. |
distal leaf sheaths persistent or fugaceous, pale brown or green, sometimes streaked red-brown, membranous to translucent, apex acute to acuminate. |
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; often proliferous, ellipsoid to ovoid, terete, 2–10.5 × 1–2.8 mm, apex acute; proximal scale empty, persistent, amplexicaulous, dissimilar to floral scales, slightly longer, often resembling an involucral bract, elliptic or lanceolate, 1.4–2.7 × 0.8–1.2 mm, apex rounded, midrib markedly thickened and broad; subproximal scale with a flower; floral scales spiraled, 13–76, 9–13 per mm of rachilla, colorless or pale brown, streaked or mottled pale brown to red-brown, midribs sometimes green, ovate, elliptic, or obovate, 0.8–2.2 × 0.5–1 mm, papery or membranous, midrib evident to prominent, apex 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 5–6 or absent, appressed to achene, white, vestigial to shorter than achene, to 0.3 mm; spinules not evident at 45X; stamens 2–3; anthers 0.2–0.45 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. |
grayish to pale olive or yellowish, often minutely brown-spotted, obovoid, trigonous, angles prominent, 0.45–0.8 × 0.3–0.55 mm, apex constricted proximal to tubercle, smooth or finely pitted at 30X. |
Tubercles | stramineous to whitish, umbonate to subconic, 0.2–0.4 × 0.2–0.5 mm, apex rounded to acute. |
gray, green, or yellowish, birettaform, trigonous, 0.05–0.1 × 0.15–0.3 mm. |
Aff | . |
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Brittonii | ), 7–37 cm × 0.2–0.6 mm, soft to firm. |
|
2n | = 10. |
= 10. |
Eleocharis geniculata |
Eleocharis brittonii |
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Phenology | Fruiting spring–winter (Mar–Dec). | Fruiting mid spring–winter. |
Habitat | Brackish creeks, canal banks, dune depressions, hammocks, irrigation ditches, lakeshores, lagoons, mangrove thickets, maritime mud flats, ditches, salt marshes | Freshwater, moist terrestrial sites, peaty ponds, swamps |
Elevation | 0–1500 m (0–4900 ft) | 0–100 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; MO; MS; SC; TN; TX
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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.) |
Preliminary studies suggest that Eleocharis brittonii may be comprised of two entities that may warrant taxonomic recognition, perhaps at the species level. Typical E. brittonii is usually robust, with floral scales pale brown and papery, bristles well developed, and achenes to 0.8 mm, clearly pitted at 30X. It is known from Alabama, Florida, Georgia, Louisiana, Mississippi, New Jersey, and South Carolina. The second variant is usually small with floral scales whitish with red-brown markings, bristles absent or poorly developed, and achenes not more than 0.6 mm, smooth at 30X. We have annotated specimens of this second variant E. sp. aff. brittonii, known from Arkansas, Florida, Georgia, Louisiana, Mississippi, Tennessee, and Texas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 101. | FNA vol. 23. |
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 | E. microcarpa var. brittonii |
Name authority | (Linnaeus) Roemer & Schultes: in J. J. Roemer et al., Syst. Veg. 2: 150. (1817) | Svenson ex Small: Man. S.E. Fl., 164. (1933) |
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