Eleocharis geniculata |
Eleocharis decumbens |
|
---|---|---|
bent spike-rush, Canada spikesedge, capitate spike-rush |
decumbent spikerush |
|
Habit | Plants tufted, without creeping rhizomes. | Plants perennial, densely tufted; rhizomes often hidden by culms and roots, fairly long, 3–4 mm thick, hard, cortex persistent, longer internodes from very short to 5 mm, scales usually clearly evident, disintegrating to fibers, 20–25 mm, papery. |
Culms | to 45 cm × 0.2–1 mm. |
terete, often with 10–18 blunt ridges when dry, 10–50 cm × 0.3–2 mm, firm to rigid, spongy. |
Leaves | distal leaf sheaths persistent, firm, distally tightly sheathing, apex acute. |
distal leaf sheaths persistent, not splitting, proximally brown or reddish, distally stramineous, brown, reddish or green, often inflated, papery, apex mostly dark red-brown, subtruncate to obtuse, often callose, tooth absent. |
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, 3–8 × 2–2.5 mm, apex acute; proximal scale amplexicaulous, entire; subproximal scale empty or with flower; floral scales appressed in fruit, 10–20, 3 per mm of rachilla, orange-brown, midrib regions often greenish, ovate, 3–3.5 × 1.5 mm, apex entire, acute, 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 6, stramineous, stout, nearly equal, mostly equaling or exceeding tubercle, (0.5–)1–2.2 mm, prominently retrorsely spinulose; stamens 3(?); anthers dark yellow to stramineous, 1.2–1.5; 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. |
falling with scales, dark brown, obpyriform, nearly eqilaterally- to greatly compressed-trigonous, angles slightly prominent, 1–1.3 × 0.75–0.9 mm, neck absent or short, finely rugulose at 20X with more than 20 horizontal ridges in vertical series, or reticulate or cancellate at 20–30X. |
Tubercles | stramineous to whitish, umbonate to subconic, 0.2–0.4 × 0.2–0.5 mm, apex rounded to acute. |
well developed, whitish, pyramidal, as high as wide to much lower than wide, 0.2–0.6 × 0.4–0.7 mm. |
2n | = 10. |
|
Eleocharis geniculata |
Eleocharis decumbens |
|
Phenology | Fruiting spring–winter (Mar–Dec). | Fruiting summer–fall. |
Habitat | Brackish creeks, canal banks, dune depressions, hammocks, irrigation ditches, lakeshores, lagoons, mangrove thickets, maritime mud flats, ditches, salt marshes | Wet fresh meadows, seeps, and lakeshores, in interior montane conifer forests and alpine zones |
Elevation | 0–1500 m (0–4900 ft) | 700–3500 m (2300–11500 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
|
CA; OR |
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 decumbens is known only from Shasta and Tulare counties in California. Although Eleocharis decumbens has long been ignored or treated as a variety of E. montevidensis, it clearly is a very distinct species, from which it differs especially in its thick rhizomes with fibrous scales and its acute floral scales. Specimens of Eleocharis decumbens without rhizomes or achenes are easily confused with the apparently closely related E. bolanderi, which often may be distinguished by culms no more than 0.5 mm wide and spikelets with scales no more than 3 mm long. The tubercles of E. decumbens are usually well differentiated from the achenes and about as high as wide; the tubercles of E. bolanderi are often poorly developed and much lower than wide. Three collections from Jackson and Klamath counties in Oregon, lack achenes but are probably E. decumbens. (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. Eleocharis |
Sibling taxa | ||
Synonyms | Scirpus geniculatus, E. capitata, E. caribaea, E. dispar | E. montevidensis var. decumbens |
Name authority | (Linnaeus) Roemer & Schultes: in J. J. Roemer et al., Syst. Veg. 2: 150. (1817) | C. B. Clarke: Bull. Misc. Inform., addit. ser. 8: 23. (1908) |
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