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dubius rush, mariposa rush, questionable rush

black needle rush, blackgrass, blackgrass rush, Gerard's rush, saltmarsh rush, saltmeadow rush

Habit Herbs, perennial, rhizomatous, 3–7.5 dm. Herbs, perennial, 2–9 dm.
Rhizomes

2–3 mm diam., not swollen.

long- creeping.

Culms

erect, terete, 2–4 mm diam., smooth or rugulose.

Cataphylls

1–2, pink to straw-colored, apex acute.

1–3.

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–)2–4;

auricles 0.4–0.6(–0.8) mm, scarious;

blade flat or somewhat channeled, 10–40 cm × 0.4–0.7 mm, margins entire.

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.

10–30(–80)-flowered, usually loose and somewhat lax, 2–16 cm;

primary bract rarely surpassing inflorescence.

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.

bracteoles 2;

tepals dark brown or blackish, lanceolate-ovate to oblong, 2.6–3.2(–3.8) mm;

inner and outer series nearly equal, apex obtuse;

stamens 6, filaments 0.4–0.7 mm, anthers 1.1–1.6(–1.8) mm;

style 0.4 mm.

Capsules

exserted, chestnut brown, 1-locular, subuloidsubulate, (2.4–)3–3.9 mm, apex tapering to subulate tip, valves separating at dehiscence.

chestnut brown or brown, 3-locular, widely ellipsoid, (2.2–)2.5–3.2(–3.5) × 1.3–1.9 mm.

Seeds

obovoid, 0.3–0.4 mm, not tailed.

dark brown, ellipsoid to lunate, 0.485–0.6(–0.67) mm, not tailed.

2n

= 40.

= ca. 80, 84.

Juncus dubius

Juncus gerardii

Phenology Fruiting early summer–late fall. Flowering and fruiting late spring–summer.
Habitat Montane meadows, riverbeds, canyons, aroyos Forming extensive colonies in exposed coastal estuary meadows and salt marshes just above high- tide line, also inland
Elevation 100–1600 m (300–5200 ft)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CO; CT; DE; IL; IN; KS; KY; MA; MD; ME; MI; MN; MO; MT; ND; NH; NJ; NY; OH; OR; OR; PA; RI; UT; VA; VT; WA; WI; BC; MB; NB; NF; NS; ON; PE; QC; SPM; Greenland; Europe; Asia
[WildflowerSearch map]
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.)

Source FNA vol. 22. FNA vol. 22.
Parent taxa Juncaceae > Juncus > subg. Septati Juncaceae > Juncus > subg. Poiophylli
Sibling taxa
J. acuminatus, J. acutiflorus, J. acutus, J. alpinoarticulatus, J. anthelatus, J. arcticus, J. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, J. brachycephalus, J. brachyphyllus, J. brevicaudatus, J. bryoides, J. bufonius, J. bulbosus, J. caesariensis, J. canadensis, J. capillaris, J. capitatus, J. castaneus, J. chlorocephalus, J. compressus, J. confusus, J. cooperi, J. coriaceus, J. covillei, J. debilis, J. dichotomus, J. diffusissimus, J. drummondii, J. dudleyi, J. effusus, J. elliottii, J. ensifolius, J. falcatus, J. filiformis, J. filipendulus, J. georgianus, J. gerardii, J. greenei, J. gymnocarpus, J. hallii, J. hemiendytus, J. howellii, J. inflexus, J. interior, J. kelloggii, J. leiospermus, J. lesueurii, J. longistylis, J. luciensis, J. macrandrus, J. macrophyllus, J. marginatus, J. maritimus, J. megacephalus, J. mertensianus, J. militaris, J. nevadensis, J. nodatus, J. nodosus, J. occidentalis, J. orthophyllus, J. oxymeris, J. parryi, J. patens, J. pelocarpus, J. pervetus, J. phaeocephalus, J. polycephalus, J. regelii, J. repens, J. roemerianus, J. scirpoides, J. secundus, J. squarrosus, J. stygius, J. subcaudatus, J. subtilis, J. supiniformis, J. tenuis, J. texanus, J. textilis, J. tiehmii, J. torreyi, J. trifidus, J. triformis, J. triglumis, J. trigonocarpus, J. uncialis, J. validus, J. vaseyi, J. xiphioides
J. acuminatus, J. acutiflorus, J. acutus, J. alpinoarticulatus, J. anthelatus, J. arcticus, J. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, J. brachycephalus, J. brachyphyllus, J. brevicaudatus, J. bryoides, J. bufonius, J. bulbosus, J. caesariensis, J. canadensis, J. capillaris, J. capitatus, J. castaneus, J. chlorocephalus, J. compressus, J. confusus, J. cooperi, J. coriaceus, J. covillei, J. debilis, J. dichotomus, J. diffusissimus, J. drummondii, J. dubius, J. dudleyi, J. effusus, J. elliottii, J. ensifolius, J. falcatus, J. filiformis, J. filipendulus, J. georgianus, J. greenei, J. gymnocarpus, J. hallii, J. hemiendytus, J. howellii, J. inflexus, J. interior, J. kelloggii, J. leiospermus, J. lesueurii, J. longistylis, J. luciensis, J. macrandrus, J. macrophyllus, J. marginatus, J. maritimus, J. megacephalus, J. mertensianus, J. militaris, J. nevadensis, J. nodatus, J. nodosus, J. occidentalis, J. orthophyllus, J. oxymeris, J. parryi, J. patens, J. pelocarpus, J. pervetus, J. phaeocephalus, J. polycephalus, J. regelii, J. repens, J. roemerianus, J. scirpoides, J. secundus, J. squarrosus, J. stygius, J. subcaudatus, J. subtilis, J. supiniformis, J. tenuis, J. texanus, J. textilis, J. tiehmii, J. torreyi, J. trifidus, J. triformis, J. triglumis, J. trigonocarpus, J. uncialis, J. validus, J. vaseyi, J. xiphioides
Synonyms J. rugulosus J. bulbosus var. gerardii, J. fucensis, J. gerardii var. pedicellatus
Name authority Engelmann Loiseleur-Deslongchamps: J. Bot. (Desvaux) 2: 284. (1809)
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