Eleocharis tricostata |
Eleocharis quadrangulata |
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three-angle spikerush, three-angle spikesedge |
four-angle spikerush, square-stem spike-rush, square-stem spikesedge |
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Habit | Plants perennial, mat-forming; rhizomes evident, fairly long, 1.5–3 mm thick, hard, cortex persistent, longer internodes 1.5–3 mm, scales disintegrating to fibers, 4–5 mm, papery. | Plants perennial; rhizomes 1.5–4 mm thick, soft to hard, longer internodes 3–8 cm, scales 5–10 mm, tubers absent. |
Culms | terete, often with 8–12 blunt ridges when dry, 20–55 cm × 0.3–1.3 mm, soft to hard. |
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 | distal leaf sheaths persistent, rarely splitting, proximally red to stramineous, distally green to reddish, papery, apex often dark reddish, subtruncate to obtuse, not callose, tooth present on some or all culms of plant, to 0.5 mm. |
distal leaf sheaths persistent, membranous, apex narrowly acute to acuminate, sometimes prolonged into a bladelike portion to 8 cm. |
Spikelets | cylindric to ovoid, 5–20 × 2–3 mm, apex rounded to subacute; proximal scale amplexicaulous, apex entire; subproximal scale empty; floral scales appressed in fruit, 20–200+, 10 per mm of rachilla, dark brown, midrib regions often stramineous or greenish, oblong, 1.7–2.5 × 1 mm, apex entire, broadly rounded, usually recurved, mostly carinate. |
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 absent; stamens 3; anthers dark yellow, 1–1.5 mm; styles 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 | falling with scales, medium to dark brown, obovoid to obpyriform, with short neck, thickly trigonous, angles prominent (keeled), 0.7–0.9 × 0.4–0.6 mm, obscurely to clearly rugulose at 10–20X with more than 20 horizontal ridges in vertical series and/or minutely cancellate at 20–30X. |
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 | brown, rudimentary, mostly apiculate, sometimes pyramidal, 0.05–0.15 × 0.15–0.2 mm. |
dark brown or whitish, deltoid to high-pyramidal or lanceoloid, 0.7–1.5 × 0.4–1 mm, often spongy. |
Eleocharis tricostata |
Eleocharis quadrangulata |
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Phenology | Fruiting late spring–summer. | Fruiting early summer–winter. |
Habitat | Wet sandy or peaty depressions, pond margins, pine barrens, savannas, mostly coastal plains | Shallow water of fresh lake and pond shores, marshes |
Elevation | 10–200 m (0–700 ft) | 10–600 m (0–2000 ft) |
Distribution |
AL; FL; GA; MA; MI; NC; NJ; NY; SC; VA
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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 | I have not seen specimens to verify reports of Eleocharis tricostata from Louisiana. In the absence of rhizomes and achenes, E. tricostata is easily mistaken for E. montevidensis. (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. 88. | FNA vol. 23, p. 120. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Eleocharis | Cyperaceae > Eleocharis > subg. Limnochloa |
Sibling taxa | ||
Synonyms | Scirpus quadrangulatus, E. quadrangulata var. crassior, Scirpus albomarginatus, Scirpus marginatus | |
Name authority | Torrey: Ann. Lyceum Nat. Hist. New York. 3: 310. (1836) | (Michaux) Roemer & Schultes: in J. J. Roemer et al., Syst. Veg. 2: 155. (1817) |
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