Eleocharis atropurpurea |
Eleocharis occulta |
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purple spike-rush |
limestone spike-rush |
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Habit | Plants tufted, without creeping rhizomes. | Plants perennial, densely cespitose; rhizomes concealed by persistent dead culm bases, often ascending, short, 3–5 mm thick, hard, cortex persistent, internodes very short, scales decaying to coarse fibers, 5–12 mm, papery. |
Culms | 2–12(–19) cm × 0.2–0.4 mm. |
subterete to slightly compressed, less than 2 times wider than thick, with 4–7 blunt ridges when dry, 27–56 cm × 0.2–0.5(–0.7) mm, firm to hard, spongy. |
Leaves | distal leaf sheaths firm, distally tightly sheathing, apex acute. |
distal leaf sheaths persistent, not splitting, proximally red, distally green to stramineous, often inflated, thinly papery to membranous, sometimes translucent, apex broadly obtuse to subtruncate, often callose, tooth absent. |
Spikelets | ovoid to ellipsoid, 2–6(–8) × 1–2.5 mm, apex acute; proximal scale with or without flower, not amplexicaulous; floral scales to 100, 15–19 per mm of rachilla, often loosely appressed, dark red-brown to stramineous, ovate to elliptic, 0.6–1.3 × 0.3–0.7 mm, membranous, apex rounded to acute. |
ovoid, 3–10 × 2–3 mm, apex acute; proximal scale amplexicaulous, apex 2-fid; subproximal scale with a flower; floral scales spreading in fruit, 20–50, 7 per mm of rachilla, medium brown, midrib region often narrowly stramineous, carinate, lanceolate-attenuate, 2–2.8 × 1 mm, apex 2-fid. |
Flowers | perianth bristles (0–)4–6, typically 4, colorless to whitish, vestigial to 1/2 as long as achene, smooth or spinuliferous; styles 2-fid. |
perianth bristles 3 or absent, stramineous to pale brown, rudimentary to 1/2 achene length, obscurely retrorsely spinulose; stamens 3; anthers orange-brown, 0.7–1.3 mm; styles 3-fid. |
Achenes | black, obovoid, biconvex, 0.3–0.5 × 0.3–0.4 mm, apex often constricted proximal to tubercle, smooth at 40X. |
falling with scales, medium or dark brown, obpyriform, nearly equilaterally obscurely trigonous or cross section nearly circular, 0.7–1 × 0.5–0.65 mm, neck distinct or rarely absent, obscurely rugulose at 10–30X, 30 or more low, blunt horizontal ridges in vertical series. |
Tubercles | stramineous to whitish, umbonate to subconic, 0.1–0.2 × 0.1–0.2 mm, apex acute. |
brown, depressed-pyramidal, often rudimentary, 0.1–0.15 × 0.2 mm. |
2n | = 20. |
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Eleocharis atropurpurea |
Eleocharis occulta |
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Phenology | Fruiting summer–fall (Jun–Sep). | Fruiting spring (Mar–May), sometimes summer (Jul). |
Habitat | Canal banks, hammocks, irrigation ditches, lake and pond margins, maritime shores, rice fields | Seasonally wet, calcareous seeps, depressions, swales, rock crevises, rocky stream beds, stream banks, wet meadows, pond margins, often on limestone |
Elevation | 0–1800 m (0–5900 ft) | 80–300 m (300–1000 ft) |
Distribution |
AL; CA; FL; GA; IA; KS; LA; MI; MO; NC; NE; NM; OK; SC; TX; WA; BC; Mexico; Central America; South America; West Indies; Europe (naturalized); Asia; Africa; Pacific Islands
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OK; TX |
Discussion | Eleocharis atropurpurea has been reported from Colorado, Montana, and Virginia; I have not seen voucher specimens. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Eleocharis occulta is very invariable in contrast to the extreme variability of E. compressa. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 102. | FNA vol. 23, p. 83. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Maculosae | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Eleocharis |
Sibling taxa | ||
Synonyms | Scirpus atropurpureus | |
Name authority | (Retzius) J. Presl & C. Presl: in C. B. Presl, Reliq. Haenk. 1: 196. (1828) | S. G. Smith: Novon 11: 247, figs. 2, 3E–K. (2001) |
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