Juncus articulatus |
Juncus acutus |
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joint-leaf rush, jointed rush |
sharp rush, spiny rush |
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Habit | Herbs, perennial, rhizomatous to nearly cespitose, 0.5–6(–10) dm. | |
Rhizomes | 2–3 mm diam., not swollen. |
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Culms | erect to decumbent (and floating), terete, 1–3 mm diam., smooth. |
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Cataphylls | 1, maroon to straw-colored, apex acute to obtuse. |
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Leaves | basal 0–2, cauline (1–)3–6; auricles 0.5–1 mm, apex rounded, scarious; blade green to straw-colored, terete, 3.5–12 cm × 0.5–1.1 mm. |
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Inflorescences | terminal panicles of 3–30(–50) heads, 3.5–8 cm, branches spreading; primary bract erect; heads 3–10-flowered, obpyramidal to hemispheric, 6–8 mm diam. |
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Flowers | tepals green to straw-colored or dark brown, ovate to lanceolate, 1.8–3 mm; outer tepals with apex acute or acuminate; inner tepals with apex acute acuminate to obtuse; stamens 6, anthers equal to filament length. |
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Capsules | exserted ca. 1 mm beyond perianth, chestnut brown to dark brown, imperfectly 3-locular, ellipsoid or ovoid, 2.8–4 mm, apex acute proximal to beak, valves separating at dehiscence. |
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Seeds | obovoid, 0.5 mm, not tailed. |
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2n | = 80. |
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Juncus articulatus |
Juncus acutus |
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Phenology | Fruiting mid summer–fall. | |
Habitat | Wet ground in ditches, lake and stream margins, and a variety of other habitats, often a calciphile | |
Elevation | 0–3000 m (0–9800 ft) | |
Distribution |
AK; AZ; CA; CO; CT; ID; IN; KY; MA; ME; MI; MN; NC; NE; NH; NJ; NM; NV; NY; OH; OR; PA; RI; SD; UT; VA; VT; WA; WV; BC; NB; NF; NS; ON; PE; QC; SPM; Eurasia
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AZ; CA; NV; South America; Mexico (Baja Calif); South Africa; Atlantic Islands
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Discussion | Juncus articulatus hybridizes with J. brevicaudatus (= J. ×fulvescens Fernald), J. alpinus (= J. ×alpiniformis Fernald), J. nodosus, and J. canadensis. Juncus articulatus var. obtusatus Engelmann appears to be intermediate with J. alpinus. It has spreading inflorescence branches but obtuse inner tepals. This may represent a backcross with J. alpinus. Recent evidence suggests that J. alpinus is a polyploid species with J. articulatus as one of its parents. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Subspecies 2 (1 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 22. | FNA vol. 22, p. 237. |
Parent taxa | Juncaceae > Juncus > subg. Septati | Juncaceae > Juncus > subg. Juncus |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | J. articulatus var. obtusatus, J. articulatus var. stolonifer, J. lampocarpus | |
Name authority | Linnaeus: Sp. Pl. 1: 327. (1753) | Linnaeus: Sp. Pl. 1: 325. (1753) |
Web links |