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thread rush

narrow-panicle rush, short-tail rush

Habit Herbs, perennial, 0.2–3.5 dm. Herbs, perennial, cespitose, 1.4–5.5(–7) dm.
Rhizomes

widely creeping, sparingly branched, 1.5–2 mm diam., nodes closely set.

Culms

terete, 1 mm diam.

erect, terete, 1–3 mm diam., smooth.

Cataphylls

several.

0–1, straw-colored to pink, apex acute.

Leaves

blade absent.

basal 1–3, cauline 1–2;

auricles 0.5–3 mm, apex rounded to truncate, scarious;

blade terete, 1.5–25 cm × 0.5–2.5 mm.

Inflorescences

3–10(–12)-flowered, loosely congested, 1–2 cm;

primary bract terete, nearly equaling to much longer than culm.

terminal panicles or racemes of 2–35 heads, 1–12 cm, branches erect;

primary bract erect;

heads 2–8-flowered, ellipsoid to narrowly obconic, 2–9 mm diam.

Flowers

pedicellate;

bracteoles broadly ovate, tepals light brown or green, lanceolate, 2.5–4.2 mm;

inner series loosely subtending capsule at maturity, slightly shorter, margins scarious;

stamens 6, filaments 0.5–0.9 mm, anthers 0.5–0.7 mm;

style 0.2 mm.

tepals green to light brown, lanceolate;

outer tepals 2.3–3.1 mm, apex acuminate to rarely obtuse;

inner tepals 2.5–3.2 mm, apex acuminate;

stamens 3 (or 6), anthers 1/4–1/2 filament length.

Capsules

tan, 3-locular, nearly globose, 2.5–3 × 1.8–2.1 mm, shorter than perianth.

exserted, chestnut brown, imperfectly 3-locular, narrowly ellipsoid to prismatic, 3.2–4.8 mm, apex acute proximal to beak, valves separating at dehiscence.

Seeds

amber, 0.5–0.6 mm, not tailed.

fusiform, 0.7–1.2 mm, tailed;

body covered with whitish translucent veil.

2n

= 40, 70, 80, 84.

= 80.

Juncus filiformis

Juncus brevicaudatus

Phenology Flowering and fruiting summer. Fruiting mid summer–fall.
Habitat Usually sandy, moist or wet soil along stream banks, pools, lakes or in meadow depressions, rarely in bogs, frequently hidden by larger vegetation Generally in acidic or peaty moist sites, including emergent shorelines and aroundg hot springs
Elevation 0–3000 m (0–9800 ft) 100–2500 m (300–8200 ft)
Distribution
from FNA
AK; CO; ID; MA; ME; MI; MN; MT; NE; NH; NJ; NY; OR; PA; UT; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; PE; QC; SK; YT; SPM; Greenland; Eurasia; Atlantic Islands (Iceland)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CO; CT; MA; MD; ME; MI; MN; MT; NC; NH; NY; OR; PA; RI; TN; UT; VA; VT; WI; WV; WY; AB; BC; MB; NB; NL; NS; ON; PE; QC; SK
[WildflowerSearch map]
[BONAP county map]
Discussion

Populations from about around hot springs in the west have been separated as Juncus tweedyi Rydberg, but no morphologic distinction appears to exist between J. tweedyi and J. brevicaudatus.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 22. FNA vol. 22.
Parent taxa Juncaceae > Juncus > subg. Genuini Juncaceae > Juncus > subg. Septati
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. dubius, J. dudleyi, J. effusus, J. elliottii, J. ensifolius, J. falcatus, 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. 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. 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
Synonyms J. canadensis var. brevicaudatus, J. canadensis var. coarctatus, J. canadensis var. kuntzei, J. coarctatus, J. kuntzei, J. tweedyi
Name authority Linnaeus: Sp. Pl. 1: 326. (1753) (Engelmann) Fernald: Rhodora 6: 35. (1904)
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