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thread rush

bulbous rush, spreading rush

Habit Herbs, perennial, 0.2–3.5 dm. Herbs, perennial, cespitose, often with basal bulblike swellings, occasionally appearing rhizomatous, 0.3–3 dm, to 10 dm when floating or submersed.
Rhizomes

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

Culms

terete, 1 mm diam.

erect or decumbent and rooting at nodes, or floating, terete, 1–2 mm diam., smooth.

Cataphylls

several.

1, straw-colored, apex acute.

Leaves

blade absent.

basal 1, cauline 0–1;

auricles 0.4–1 mm, apex acute, scarious;

blade terete, occasionally filiform, flaccid, forming carpets, 2–10 cm × 0.8–1.4 mm.

Inflorescences

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

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

terminal racemes of 1–8(–30) heads, or single head, 2–10 cm, branches erect;

primary bract erect;

heads 2–6(–15)-flowered, obconic, 4.5–6.5 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.

often forming bulbils;

tepals pale brown, ovate to lanceolate or inner oblong, 2–3.6 mm, nearly equal, apex acute to obtuse;

stamens 3 or 6, anthers 3/4 to equal filament length.

Capsules

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

equaling perianth or exserted (to 0.5 mm beyond tepals), chestnut brown, 1-locular, cylindric, 2.5–4 mm, apex obtuse proximal to beak, valves separating at dehiscence.

Seeds

amber, 0.5–0.6 mm, not tailed.

ellipsoid, 0.5–0.6 mm, not tailed;

body clear yellow-brown.

2n

= 40, 70, 80, 84.

Juncus filiformis

Juncus bulbosus

Phenology Flowering and fruiting summer. Fruiting mid summer–early 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 Margins and siliceous or peaty shores of pools and streams, often floating
Elevation 0–3000 m (0–9800 ft) 0–200 m (0–700 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
OR; WA; BC; NF; NS; SPM; Europe; n Africa [Probably introduced in North America]
[BONAP county map]
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. brevicaudatus, J. bryoides, J. bufonius, 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. kockii, J. supinus
Name authority Linnaeus: Sp. Pl. 1: 326. (1753) Linnaeus: Sp. Pl. 1: 327. (1753)
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