Eleocharis atropurpurea |
Eleocharis equisetoides |
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purple spike-rush |
horsetail spike-rush, horsetail spikesedge, jointed spike-rush, jointed spike-rush (spikesedge), jointed spikesedge, knotted spike-rush |
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Habit | Plants tufted, without creeping rhizomes. | Plants perennial; rhizomes 2–4 mm thick, soft to firm, longer internodes 2–8 cm, scales persistent, 7–8 mm, membranous, tubers absent. |
Culms | 2–12(–19) cm × 0.2–0.4 mm. |
terete, 50–100 cm × 5–8.4 mm, soft to firm, obscurely to clearly septate-nodulose throughout, internally hollow with complete transverse septa, closer together near the spikelet; plants never forming filiform, flaccid culms. |
Leaves | distal leaf sheaths firm, distally tightly sheathing, apex acute. |
distal leaf sheaths persistent, membranous to thinly papery, apex acute to slightly acuminate. |
Spikelets | 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. |
not proliferous, 20–45 × 4–5(–8) mm; rachilla joints bearing prominent winglike remnants of floral scales; proximal scale empty, amplexicaulous, (2–)2.8–4.9 mm; floral scales 85–160, 1–3 per mm of rachilla, stramineous to pale brown, usually with pale to dark brown submarginal band, obovate to oblong, (4.8–)5.2–7 × 3–4.4 mm, cartilaginous, often membranous toward margins, margins broadly translucent, membranous, apex rounded to obtuse. |
Flowers | perianth bristles (0–)4–6, typically 4, colorless to whitish, vestigial to 1/2 as long as achene, smooth or spinuliferous; styles 2-fid. |
perianth bristles 3–8, stramineous to reddish, slender, vestigial to 2.5 mm, shorter than to equaling achene, smooth or obscurely retrorsely spinulose; anthers stramineous to red-striated, 2.6–3.2 mm; styles 2–3-fid. |
Achenes | black, obovoid, biconvex, 0.3–0.5 × 0.3–0.4 mm, apex often constricted proximal to tubercle, smooth at 40X. |
yellowish to reddish brown, obovoid, biconvex to obscurely compressed trigonous, 1.8–2.3 × 1.4–1.9 mm, obscurely sculptured or sometimes partially smooth at 10–15X, each face with 20–40 rows of linear, transversely elongated cells, lines separating cells obscure, apex with very short neck 0.6–0.8 mm wide. |
Tubercles | stramineous to whitish, umbonate to subconic, 0.1–0.2 × 0.1–0.2 mm, apex acute. |
dark brown, lamelliform, high-deltoid, 0.6–1.1 × 0.5–0.7 mm. |
2n | = 20. |
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Eleocharis atropurpurea |
Eleocharis equisetoides |
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Phenology | Fruiting summer–fall (Jun–Sep). | Fruiting late spring–late fall. |
Habitat | Canal banks, hammocks, irrigation ditches, lake and pond margins, maritime shores, rice fields | Fresh ponds, lakes, marshes, streams, ditches, cypress swamps |
Elevation | 0–1800 m (0–5900 ft) | 10–500 m (0–1600 ft) |
Distribution |
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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AL; CA; CT; FL; GA; IN; LA; MA; MD; MI; MO; MS; NC; NY; RI; SC; TX; VA; WI; ON
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Discussion | 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.) |
We have not seen voucher specimens for reports of Eleocharis equistoides from Arkansas and Tennessee. It is probably extirpated from Illinois, Missouri, and Wisconsin. Contrary to previous decriptions, sectioning of the culm reveals that the distance between the septa near the spikelet cannot be used to distinguish the two septate species, E. equisetoides and E. interstincta, which when achenes are absent are better distinguished by the septate-nodulose distal parts of the culms of E. equisetiodes. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 102. | FNA vol. 23. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Maculosae | Cyperaceae > Eleocharis > subg. Limnochloa |
Sibling taxa | ||
Synonyms | Scirpus atropurpureus | Scirpus equisetoides, E. elliottii |
Name authority | (Retzius) J. Presl & C. Presl: in C. B. Presl, Reliq. Haenk. 1: 196. (1828) | (Elliott) Torrey: Ann. Lyceum Nat. Hist. New York 3: 296. (1836) |
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