Juncus articulatus |
Juncus mertensianus |
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joint-leaf rush, jointed rush |
Mertens' rush |
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Habit | Herbs, perennial, rhizomatous to nearly cespitose, 0.5–6(–10) dm. | Herbs, perennial, rhizomatous to cespitose, 0.5–4 dm. |
Rhizomes | 2–3 mm diam., not swollen. |
1–2 mm diam., not swollen. |
Culms | erect to decumbent (and floating), terete, 1–3 mm diam., smooth. |
erect, terete, 1–3 mm diam., smooth. |
Cataphylls | 1, maroon to straw-colored, apex acute to obtuse. |
0–1, straw-colored to chestnut brown, apex acute. |
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. |
basal 1–2, cauline 0–1; auricles 1–1.2 mm, apex rounded to acute, membranaceous or scarious; blade green to straw-colored, terete, 3–15 cm × 0.3–0.6 mm. |
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. |
terminal single head (rarely cluster of 2 heads), 0.5–1.6 cm; primary bract erect; heads 12–60-flowered, spheric (to hemispheric), 4.5–15 mm diam. |
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. |
tepals dark purplish brown to black, lanceolate to lance-ovate, apex acute, mucro subulate; outer tepals 2.4–4.9 mm; inner tepals 2.3–4.3 mm; stamens 6, anthers 1/4 to equal filament length. |
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. |
included or slightly exserted, chestnut brown, 1-locular, obovoid, 1.9–3.5 mm, apex obtuse or rounded, valves separating at dehiscence, fertile throughout or only proximal to middle. |
Seeds | obovoid, 0.5 mm, not tailed. |
ellipsoid, 0.4–0.5 mm, not tailed; body clear yellow-brown. |
2n | = 80. |
= 40. |
Juncus articulatus |
Juncus mertensianus |
|
Phenology | Fruiting mid summer–fall. | Fruiting mid summer–fall. |
Habitat | Wet ground in ditches, lake and stream margins, and a variety of other habitats, often a calciphile | Montane to alpine meadows, stream banks, lake margins, and conifer woods |
Elevation | 0–3000 m (0–9800 ft) | (400–)1900–3300 m ((1300–)6200–10800 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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AK; AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC; NT; SK; YT
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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.) |
Populations from southern California with brown tepals, anthers equaling filaments, and rounded to acute, translucent auricles have been separated as Juncus duranii; the typical form is so highly variable, however, that it can easily accommodate this local form. This species passes into Juncus nevadensis and has often been combined with that species (F. J. Hermann 1964). The two species can generally be separated, and we are following those treatments (F. J. Hermann 1975; A. Cronquist et al. 1972+, vol. 6). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 22. | FNA vol. 22, p. 252. |
Parent taxa | Juncaceae > Juncus > subg. Septati | Juncaceae > Juncus > subg. Septati |
Sibling taxa | ||
Synonyms | J. articulatus var. obtusatus, J. articulatus var. stolonifer, J. lampocarpus | J. duranii, J. mertensianus var. duranii, J. mertensianus var. filifolius, J. slwookoorum |
Name authority | Linnaeus: Sp. Pl. 1: 327. (1753) | Bongard: Mém. Acad. Imp. Sci. St.-Pétersbourg, Sér. 6, Sci. Math. 2: 167. (1833) |
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