Juncus dubius |
Juncus mertensianus |
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dubius rush, mariposa rush, questionable rush |
Mertens' rush |
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Habit | Herbs, perennial, rhizomatous, 3–7.5 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, terete, 2–4 mm diam., smooth or rugulose. |
erect, terete, 1–3 mm diam., smooth. |
Cataphylls | 1–2, pink to straw-colored, apex acute. |
0–1, straw-colored to chestnut brown, apex acute. |
Leaves | basal 1–2, cauline 1–2; auricles 1–4.9 mm, , apex rounded, membranaceous; blade green to straw-colored, terete, 20–30 cm × 1.5–4 mm, rugulose or smooth. |
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 25–66 heads, 7–13 cm, branches spreading; primary bract erect; heads 6–10-flowered, hemispheric to obovoid, 5–10 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 straw-colored to brown, lanceolate, apex acuminate; outer tepals (2–)2.5–3.4 mm; inner tepals (2–)2.6–3.6 mm; stamens 6, anthers 1.5–2 times 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, chestnut brown, 1-locular, subuloidsubulate, (2.4–)3–3.9 mm, apex tapering to subulate tip, 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, 0.3–0.4 mm, not tailed. |
ellipsoid, 0.4–0.5 mm, not tailed; body clear yellow-brown. |
2n | = 40. |
= 40. |
Juncus dubius |
Juncus mertensianus |
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Phenology | Fruiting early summer–late fall. | Fruiting mid summer–fall. |
Habitat | Montane meadows, riverbeds, canyons, aroyos | Montane to alpine meadows, stream banks, lake margins, and conifer woods |
Elevation | 100–1600 m (300–5200 ft) | (400–)1900–3300 m ((1300–)6200–10800 ft) |
Distribution |
CA
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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 dubius has rugulose stems and leaves throughout most of its range, but on the periphery (in Mariposa, San Diego, and Sonoma counties, California) the plants are smooth. (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 | ||
Sibling taxa | ||
Synonyms | J. rugulosus | J. duranii, J. mertensianus var. duranii, J. mertensianus var. filifolius, J. slwookoorum |
Name authority | Engelmann | Bongard: Mém. Acad. Imp. Sci. St.-Pétersbourg, Sér. 6, Sci. Math. 2: 167. (1833) |
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