Eleocharis engelmannii |
Eleocharis cylindrica |
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Engelman spikerush, Engelmann's spike-rush, Engelmann's spikesedge, englemann's spike-rush |
cylinder spikerush |
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Habit | Plants perennial; rhizomes evident, 1 mm thick, firm, cortex unknown, internodes unknown, scales fugacious, 5 mm, membranous. | |
Culms | 2–40 cm × 0.5–1.5(–2) mm. |
terete, often with a few blunt ridges when dry, 20–50 cm × 0.2–0.7 mm, soft, spongy. |
Leaves | apex of distal leaf sheath obtuse to acute, tooth to 0.3 mm. |
distal leaf sheaths persistent, not splitting, proximally red or stramineous, distally green, membranous, apex usually reddish, subtruncate to obtuse, not callose, tooth present, to 0.4 mm. |
Spikelets | lanceoloid to subcylindric or ovoid, 5–10(–20) × 2–3(–4) mm, apex acute (to rounded); proximal scale empty, encircling ca. 2/3 of culm; floral scales 25–100(–200), 8–12 per mm of rachilla, orangebrown to stramineous, 2(–2.5) × 1–1.3 mm, midribs mostly keeled, ovate, apex narrowly rounded to subacute. |
narrowly lanceoloid, narrowly ovoid, or narrowly cylindric, 4–10 × 1–1.5 mm, apex narrowly acute; proximal scale amplexicaulous or clasping 3/4 of culm, entire; subproximal scale empty or with flower; floral scales spreading in fruit, 20–80, 5–6 per mm of rachilla, orange-brown, midrib regions stramineous, narrowly ovate-lanceolate, 1.5–2 × 0.8 mm, entire, apex acute, not carinate. |
Flowers | perianth bristles present or often absent, 5–8, brown, stout, rudimentary to slightly exceeding tubercle; stamens (2–)3; anthers brown to yellow, 0.3–0.7(–1) mm; styles 2–3-fid. |
perianth bristles 3–6, stramineous, stout, unequal, rudimentary to less than 1/2 achene length; stamens 3; anthers stramineous, 0.7–1.4 mm; styles 3-fid. |
Achenes | 0.9–1.1(–1.5) × 0.7–1.1 mm. |
falling with scales, stramineous, ellipsoid, compressed-trigonous, angles prominent (keeled), 0.6–0.65 × 0.4–0.45 mm, base narrowed, neck long, smooth at 40X. |
Tubercles | depressed, subdeltoid, 0.1–0.3(–0.4) × 0.6–0.9(–1) mm, 1/10–2/5 as high as wide, 1/4 or less as high as achene, 9/10 as wide as achene, very rarely 2/5 as high as achene (in E. engelmannii var. robusta). |
brown, pyramidal, as high as wide to greatly depressed, 0.1–0.25 × 0.15–0.2 mm. |
2n | = 10. |
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Eleocharis engelmannii |
Eleocharis cylindrica |
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Phenology | Fruiting spring–fall. | Fruiting spring–summer. |
Habitat | Fresh shores, marshes, disturbed places | Ephemeral pools in old rock quarry |
Elevation | 30–2400 m (100–7900 ft) | 300 m (1000 ft) |
Distribution |
AL; AR; AZ; CA; CO; CT; DC; DE; IA; ID; IL; IN; KS; KY; MA; MD; MI; MN; MO; MS; MT; ND; NE; NH; NJ; NM; NY; OH; OK; OR; PA; RI; TN; TX; VA; WA; WI; WV; AB; BC; MB; ON
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TX; South America (Argentina, Paraguay) |
Discussion | Robust plants known only from Missouri and described as Eleocharis engelmannii var. robusta have well-developed caudices, culms to 2 mm wide (pressed), spikelets to 2 cm, floral scales to 2.5 mm and slightly cartilaginous, styles mostly trifid, achenes to 1.5 × 1 mm, and tubercles 0.3–0.5 × 0.7–1 mm and to 2/5 as high as achene. Some specimens are intermediate between E. engelmannii and E. obtusa, or rarely with E. lanceolata. I have not seen specimens to verify literature reports of E. engelmannii from Manitoba, Connecticut, Delaware, Idaho, New Hampshire, North Carolina, Oregon, Rhode Island, South Carolina, South Dakota, or Vermont. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Eleocharis cylindrica is synonymous with E. spegazzinii Barros, which was described from temperate South America (E. R. Guaglianone and O. Ueno 1990). It is very uncommon in North America, where it has been confirmed from Aransas, Burnet, and Cameron counties in Texas; reports from Lubbock and Presidio counties have not been confirmed. The report from New Mexico cannot be confirmed because the specimens lack achenes. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 104. | FNA vol. 23, p. 81. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Ovatae | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Eleocharis |
Sibling taxa | ||
Synonyms | E. engelmannii var. detonsa, E. engelmannii var. monticola, E. engelmannii var. robusta, E. monticola, E. monticola var. leviseta, E. ovata var. detonsa | E. texana |
Name authority | Steudel: Syn. Pl. Glumac. 2: 79. (1855) | Buckley: Proc. Acad. Nat. Sci. Philadelphia 14: 10. (1863) |
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