Juncus brachycephalus |
Juncus articulatus |
|
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small-head rush |
joint-leaf rush, jointed rush |
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Habit | Herbs, perennial, cespitose, 2–7 dm. | Herbs, perennial, rhizomatous to nearly cespitose, 0.5–6(–10) dm. |
Rhizomes | 2–3 mm diam., not swollen. |
|
Culms | erect, 1–4 mm diam., smooth. |
erect to decumbent (and floating), terete, 1–3 mm diam., smooth. |
Cataphylls | 1–2, straw-colored to pink, apex acute. |
1, maroon to straw-colored, apex acute to obtuse. |
Leaves | basal 1–3, cauline 1–2; auricles 0.6–1.5 mm, apex rounded, scarious; blade terete to compressed, 0.2–12 cm × 0.5–2 mm. |
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 | panicles of 5–80 heads, 5–25 cm, branches ascending; primary bract erect; heads 2–6-flowered, ellipsoid to obovoid, 2–5 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 green to light brown, lanceolate; outer tepals 1.8–2.5 mm, apex obtuse to nearly acute; inner tepals 2–2.8 mm, apex obtuse to nearly acute; stamens 3 or 6, anthers 1/2 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 | exserted, chestnut to dark brown, imperfectly 3-locular, obconic, 2.4–3.8 mm, apex acute proximal to beak, 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 | ellipsoid to fusiform, 0.8–1.2 mm, tailed; body covered with whitish translucent veil. |
obovoid, 0.5 mm, not tailed. |
2n | = 80. |
= 80. |
Juncus brachycephalus |
Juncus articulatus |
|
Phenology | Fruiting summer–early fall. | Fruiting mid summer–fall. |
Habitat | Calcareous marshes, wet meadows, and wetland shores | Wet ground in ditches, lake and stream margins, and a variety of other habitats, often a calciphile |
Elevation | 100–200 m (300–700 ft) | 0–3000 m (0–9800 ft) |
Distribution |
AL; CO; CT; GA; IL; IN; MA; ME; MI; MN; NC; ND; NH; NJ; NY; OH; OK; PA; TN; VA; VT; WI; WV; NB; NS; ON; QC;
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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 | Juncaceae > Juncus > subg. Septati | Juncaceae > Juncus > subg. Septati |
Sibling taxa | ||
Synonyms | J. canadensis var. brachycephalus | J. articulatus var. obtusatus, J. articulatus var. stolonifer, J. lampocarpus |
Name authority | (Engelmann) Buchenau: Botanische Jahrbucher fur Systematik, Pflanzengeschichte und Pflanzengeographie 12: 268. (1890) | Linnaeus: Sp. Pl. 1: 327. (1753) |
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