Juncus acutiflorus |
Juncus articulatus |
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sharpflower rush |
joint-leaf rush, jointed rush |
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Habit | Herbs, perennial, rhizomatous, to 8 dm. | Herbs, perennial, rhizomatous to nearly cespitose, 0.5–6(–10) dm. |
Rhizomes | 5–6 mm diam., nodes not swollen. |
2–3 mm diam., not swollen. |
Culms | erect, terete, 3 mm diam., smooth. |
erect to decumbent (and floating), terete, 1–3 mm diam., smooth. |
Cataphylls | 1, straw-colored, apex acute. |
1, maroon to straw-colored, apex acute to obtuse. |
Leaves | basal 1, cauline 2; auricles 0.5 mm, apex rounded, cartilaginous; blade 7–45 cm x 1–2 mm, terete, not scabrous. |
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. |
Inflorescences | terminal panicles of 70–120 heads, 6–10 cm, branches ascending; primary bract erect; heads 3–5(–8)-flowered, obconic, 2–4 mm diam. |
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. |
Flowers | tepals dark reddish brown, lanceolate, apex acuminate to subulate tipte; outer tepals 1.9–2.2 mm; inner tepals 2–2.3 mm; stamens 6, anthers 2 times filament length. |
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. |
Capsules | inserted with beak exserted, straw-colored, 1-locular, narrowly ovoid, 2.3–2.4 mm, tapering to subulate tip, valves separating at dehiscence. |
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. |
Seeds | narrowly ovoid, 0.5–0.6 mm, not tailed; body clear yellow-brown. |
obovoid, 0.5 mm, not tailed. |
2n | = 80. |
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Juncus acutiflorus |
Juncus articulatus |
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Phenology | Fruiting fall. | Fruiting mid summer–fall. |
Habitat | Wet woods | Wet ground in ditches, lake and stream margins, and a variety of other habitats, often a calciphile |
Elevation | 0–10 m (0–0 ft) | 0–3000 m (0–9800 ft) |
Distribution |
NF; SPM; Europe; Asia; Africa |
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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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.) |
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Source | FNA vol. 22. | FNA vol. 22. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | J. articulatus var. obtusatus, J. articulatus var. stolonifer, J. lampocarpus | |
Name authority | Ehrhart: in G. F. Hoffmann, Deutschl. Fl. 1: 125. (1791) | Linnaeus: Sp. Pl. 1: 327. (1753) |
Web links |