Eleocharis engelmannii |
Eleocharis quadrangulata |
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Engelman spikerush, Engelmann's spike-rush, Engelmann's spikesedge, englemann's spike-rush |
four-angle spikerush, square-stem spike-rush, square-stem spikesedge |
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Habit | Plants perennial; rhizomes 1.5–4 mm thick, soft to hard, longer internodes 3–8 cm, scales 5–10 mm, tubers absent. | |
Culms | 2–40 cm × 0.5–1.5(–2) mm. |
acutely quadrangular, (30–)45–105 cm × (1–)2–5.4 mm, soft to firm, internally spongy, transverse septa incomplete; plants never forming filiform, flaccid culms. |
Leaves | apex of distal leaf sheath obtuse to acute, tooth to 0.3 mm. |
distal leaf sheaths persistent, membranous, apex narrowly acute to acuminate, sometimes prolonged into a bladelike portion to 8 cm. |
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. |
not proliferous, (15–)20–76 × 3–5(–6) mm; rachilla joints bearing obscure winglike remnants of floral scales; proximal scale empty, amplexicaulous, (1–)2.2–5.4 mm; floral scales (28–)45–135, 2–3 per mm of rachilla, stramineous to pale brown, usually with pale to dark brown submarginal band, midrib region sometimes greenish, broadly obovate to ovate, (4–)4.5–6.2 × 2.8–5 mm, subcartilaginous, apex rounded to obtuse. |
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 6–7, whitish to brown, slender, often markedly unequal, shorter than achene or some equalling tubercle, sparsely retrorsely spinulose to smooth; anthers stramineous to red-brown, 2.3–2.9 mm; styles 3-fid, sometimes 2-fid. |
Achenes | 0.9–1.1(–1.5) × 0.7–1.1 mm. |
yellow or pale green to brown or purplish, biconvex, obovoid to obpyriform, 1.8–3 × 1.3–2 mm, almost smooth to markedly sculptured at 10–15X, each face with 19–38 rows of almost linear, transversely elongated cells, which are sometimes isodiametric at achene base, apex often constricted to neck 0.3–0.4 mm wide. |
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). |
dark brown or whitish, deltoid to high-pyramidal or lanceoloid, 0.7–1.5 × 0.4–1 mm, often spongy. |
2n | = 10. |
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Eleocharis engelmannii |
Eleocharis quadrangulata |
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Phenology | Fruiting spring–fall. | Fruiting early summer–winter. |
Habitat | Fresh shores, marshes, disturbed places | Shallow water of fresh lake and pond shores, marshes |
Elevation | 30–2400 m (100–7900 ft) | 10–600 m (0–2000 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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AR; CA; CT; DE; FL; GA; IL; IN; KY; LA; MA; MI; MO; MS; NC; NJ; NY; OH; OK; OR; PA; SC; TX; VA; WI; WV; ON; s to c Mexico
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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.) |
We have not seen voucher specimens for the reports of Eleocharis quadrangulata from Kansas. Plants with greenish achenes, longer bristles, and longer anthers than the average are known from Tennessee. The tubercles of Eleocharis quadrangulata are often spongy as in E. obtusetrigona. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 104. | FNA vol. 23, p. 120. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Ovatae | Cyperaceae > Eleocharis > subg. Limnochloa |
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 | Scirpus quadrangulatus, E. quadrangulata var. crassior, Scirpus albomarginatus, Scirpus marginatus |
Name authority | Steudel: Syn. Pl. Glumac. 2: 79. (1855) | (Michaux) Roemer & Schultes: in J. J. Roemer et al., Syst. Veg. 2: 155. (1817) |
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