Juncus dubius |
Juncus supiniformis |
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dubius rush, mariposa rush, questionable rush |
hair-leaf rush, hairy-leaf rush, spreading rush |
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Habit | Herbs, perennial, rhizomatous, 3–7.5 dm. | Herbs, perennial, cespitose or matted, often decumbent, rooting at proximal nodes or floating, 0.3–5 dm. |
Rhizomes | 2–3 mm diam., not swollen. |
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Culms | erect, terete, 2–4 mm diam., smooth or rugulose. |
erect, decumbent and rooting at nodes, or floating, terete, 1–2 mm diam., smooth. |
Cataphylls | 1–2, pink to straw-colored, apex acute. |
0 or 1–2, straw-colored, 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 1–3, cauline 1–4; auricles 0.8–2.1 mm, apex rounded to acute, membranaceous; blade terete, 3.7–15 cm × 0.4–1.3 mm, occasionally with filiform, flaccid, and floating leaves to 60 cm. |
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 racemes of 2–9 heads, 2–10 cm, branches erect; primary bract erect; heads 2–12-flowered, obconic or rarely hemispheric, 4–13 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 light brown or greenish to reddish brown, linear to narrowly lanceolate, apex acute to acuminate-subulate; outer tepals (2.1–)2.8–4.9 mm; inner tepals (2.1–)2.8–5.5 mm; stamens 3 or 6, anthers 1/2–3/4 filament length. |
Capsules | exserted, chestnut brown, 1-locular, subuloidsubulate, (2.4–)3–3.9 mm, apex tapering to subulate tip, valves separating at dehiscence. |
usually exserted, dark brown, 1-locular, ovoid to oblong, (3.2–)3.5–6.1 mm, apex acute to acuminate proximal to beak, valves separating at dehiscence. |
Seeds | obovoid, 0.3–0.4 mm, not tailed. |
narrowly obovoid to obovoid, 0.6–0.7 mm, not tailed; body clear yellow-brown.. |
n | = ca. 30, ca. 50–60, 2n = ca. 112. |
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2n | = 40. |
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Juncus dubius |
Juncus supiniformis |
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Phenology | Fruiting early summer–late fall. | Fruiting mid summer–fall. |
Habitat | Montane meadows, riverbeds, canyons, aroyos | Pond, lake and river shores, marshes, bogs, and ditches |
Elevation | 100–1600 m (300–5200 ft) | 0–1000 m (0–3300 ft) |
Distribution |
CA
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AK; CA; OR; WA; BC
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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.) |
The northern California and southern Oregon populations (Juncus supiniformis in the strict sense) form long filiform leaves before flowering, are shorter, and have smaller flowers than the northern populations. Except for the filiform leaves, the variation in sizes appears to follow a rough latitudinal cline with the largest plants and largest flowers in Alaska. Flowers of Juncus supiniformis often form bulbils. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 22. | FNA vol. 22. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | J. rugulosus | J. oreganus, J. paucicapitatus |
Name authority | Engelmann | Engelmann |
Web links |
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