Eleocharis engelmannii |
Eleocharis flavescens |
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Engelman spikerush, Engelmann's spike-rush, Engelmann's spikesedge, englemann's spike-rush |
pale spike-rush, wrinkle-sheath spike-rush, yellow spikerush, yellow spikesedge |
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Habit | Plants with creeping rhizomes 0.5–1 mm thick. | |||||
Culms | 2–40 cm × 0.5–1.5(–2) mm. |
3–42 cm × 0.3–0.6 mm. |
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Leaves | apex of distal leaf sheath obtuse to acute, tooth to 0.3 mm. |
distal leaf sheaths often disintegrating, thinly membranous-translucent, inflated distally, often wrinkled, apex blunt. |
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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. |
ellipsoid, 1.5–9 × 1–3.5 mm, apex acute to acuminate; proximal scale without flower, not amplexicaulous; floral scales to 65, 5–7 per mm of rachilla, loosely appressed to appressed, elliptic, 1–3 × 0.4–1.6 mm, membranous, apex acute. |
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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 (0–)5–8, typically 7, white to stramineous, spinules dense to few; styles 2-fid, rarely 3-fid. |
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Achenes | 0.9–1.1(–1.5) × 0.7–1.1 mm. |
stramineous to green or dark brown, biconvex, rarely trigonous, obovoid to obpryiform, 0.4–1.1 × 0.3–0.8 mm, very finely reticulate at 40X. |
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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). |
whitish to stramineous or green, 0.2–0.7 × 0.2–0.4 mm, apex acute to acuminate. |
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2n | = 10. |
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Eleocharis engelmannii |
Eleocharis flavescens |
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Phenology | Fruiting spring–fall. | |||||
Habitat | Fresh shores, marshes, disturbed places | |||||
Elevation | 30–2400 m (100–7900 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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AL; AR; AZ; CA; CT; DE; FL; GA; ID; IL; IN; LA; MA; MD; ME; MI; MN; MS; MT; NC; NH; NJ; NY; OH; PA; RI; SC; TX; UT; VA; VT; WI; WY; NB; NS; ON; QC; South America; temperate North America; West Indies
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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.) |
Varieties 2 (2 in the flora). The varieties of Eleocharis flavescens are difficult to delimit, especially in the south, and identifications of some specimens to variety are problematic. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 23, p. 104. | FNA vol. 23, p. 100. | ||||
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Ovatae | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Maculosae | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | E. engelmannii var. detonsa, E. engelmannii var. monticola, E. engelmannii var. robusta, E. monticola, E. monticola var. leviseta, E. ovata var. detonsa | Scirpus flavescens | ||||
Name authority | Steudel: Syn. Pl. Glumac. 2: 79. (1855) | (Poiret) Urban: Symb. Antill. 4: 116. (1903) | ||||
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