Eleocharis quadrangulata |
Eleocharis atropurpurea |
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four-angle spikerush, square-stem spike-rush, square-stem spikesedge |
purple spike-rush |
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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. | Plants tufted, without creeping rhizomes. |
Culms | 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. |
2–12(–19) cm × 0.2–0.4 mm. |
Leaves | distal leaf sheaths persistent, membranous, apex narrowly acute to acuminate, sometimes prolonged into a bladelike portion to 8 cm. |
distal leaf sheaths firm, distally tightly sheathing, apex acute. |
Spikelets | 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. |
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. |
Flowers | 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. |
perianth bristles (0–)4–6, typically 4, colorless to whitish, vestigial to 1/2 as long as achene, smooth or spinuliferous; styles 2-fid. |
Achenes | 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. |
black, obovoid, biconvex, 0.3–0.5 × 0.3–0.4 mm, apex often constricted proximal to tubercle, smooth at 40X. |
Tubercles | dark brown or whitish, deltoid to high-pyramidal or lanceoloid, 0.7–1.5 × 0.4–1 mm, often spongy. |
stramineous to whitish, umbonate to subconic, 0.1–0.2 × 0.1–0.2 mm, apex acute. |
2n | = 20. |
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Eleocharis quadrangulata |
Eleocharis atropurpurea |
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Phenology | Fruiting early summer–winter. | Fruiting summer–fall (Jun–Sep). |
Habitat | Shallow water of fresh lake and pond shores, marshes | Canal banks, hammocks, irrigation ditches, lake and pond margins, maritime shores, rice fields |
Elevation | 10–600 m (0–2000 ft) | 0–1800 m (0–5900 ft) |
Distribution |
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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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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Discussion | 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.) |
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.) |
Source | FNA vol. 23, p. 120. | FNA vol. 23, p. 102. |
Parent taxa | Cyperaceae > Eleocharis > subg. Limnochloa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Maculosae |
Sibling taxa | ||
Synonyms | Scirpus quadrangulatus, E. quadrangulata var. crassior, Scirpus albomarginatus, Scirpus marginatus | Scirpus atropurpureus |
Name authority | (Michaux) Roemer & Schultes: in J. J. Roemer et al., Syst. Veg. 2: 155. (1817) | (Retzius) J. Presl & C. Presl: in C. B. Presl, Reliq. Haenk. 1: 196. (1828) |
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