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small-head rush

joint-leaf rush, jointed rush

Habit Herbs, perennial, cespitose, 2–7 dm. Herbs, perennial, rhizomatous to nearly cespitose, 0.5–6(–10) dm.
Rhizomes

2–3 mm diam., not swollen.

Culms

erect, 1–4 mm diam., smooth.

erect to decumbent (and floating), terete, 1–3 mm diam., smooth.

Cataphylls

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

1, maroon to straw-colored, apex acute to obtuse.

Leaves

basal 1–3, cauline 1–2;

auricles 0.6–1.5 mm, apex rounded, scarious;

blade terete to compressed, 0.2–12 cm × 0.5–2 mm.

basal 0–2, cauline (1–)3–6;

auricles 0.5–1 mm, apex rounded, scarious;

blade green to straw-colored, terete, 3.5–12 cm × 0.5–1.1 mm.

Inflorescences

panicles of 5–80 heads, 5–25 cm, branches ascending;

primary bract erect;

heads 2–6-flowered, ellipsoid to obovoid, 2–5 mm diam.

terminal panicles of 3–30(–50) heads, 3.5–8 cm, branches spreading;

primary bract erect;

heads 3–10-flowered, obpyramidal to hemispheric, 6–8 mm diam.

Flowers

tepals green to light brown, lanceolate;

outer tepals 1.8–2.5 mm, apex obtuse to nearly acute;

inner tepals 2–2.8 mm, apex obtuse to nearly acute;

stamens 3 or 6, anthers 1/2 filament length.

tepals green to straw-colored or dark brown, ovate to lanceolate, 1.8–3 mm;

outer tepals with apex acute or acuminate;

inner tepals with apex acute acuminate to obtuse;

stamens 6, anthers equal to filament length.

Capsules

exserted, chestnut to dark brown, imperfectly 3-locular, obconic, 2.4–3.8 mm, apex acute proximal to beak, valves separating at dehiscence.

exserted ca. 1 mm beyond perianth, chestnut brown to dark brown, imperfectly 3-locular, ellipsoid or ovoid, 2.8–4 mm, apex acute proximal to beak, valves separating at dehiscence.

Seeds

ellipsoid to fusiform, 0.8–1.2 mm, tailed;

body covered with whitish translucent veil.

obovoid, 0.5 mm, not tailed.

2n

= 80.

= 80.

Juncus brachycephalus

Juncus articulatus

Phenology Fruiting summer–early fall. Fruiting mid summer–fall.
Habitat Calcareous marshes, wet meadows, and wetland shores Wet ground in ditches, lake and stream margins, and a variety of other habitats, often a calciphile
Elevation 100–200 m (300–700 ft) 0–3000 m (0–9800 ft)
Distribution
from FNA
AL; CO; CT; GA; IL; IN; MA; ME; MI; MN; NC; ND; NH; NJ; NY; OH; OK; PA; TN; VA; VT; WI; WV; NB; NS; ON; QC;
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; AZ; CA; CO; CT; ID; IN; KY; MA; ME; MI; MN; NC; NE; NH; NJ; NM; NV; NY; OH; OR; PA; RI; SD; UT; VA; VT; WA; WV; BC; NB; NF; NS; ON; PE; QC; SPM; Eurasia
[WildflowerSearch map]
[BONAP county map]
Discussion

Juncus articulatus hybridizes with J. brevicaudatus (= J. ×fulvescens Fernald), J. alpinus (= J. ×alpiniformis Fernald), J. nodosus, and J. canadensis.

Juncus articulatus var. obtusatus Engelmann appears to be intermediate with J. alpinus. It has spreading inflorescence branches but obtuse inner tepals. This may represent a backcross with J. alpinus. Recent evidence suggests that J. alpinus is a polyploid species with J. articulatus as one of its parents.

(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. Septati
Sibling taxa
J. acuminatus, J. acutiflorus, J. acutus, J. alpinoarticulatus, J. anthelatus, J. arcticus, J. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, 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. 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. 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. 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. brachycephalus J. articulatus var. obtusatus, J. articulatus var. stolonifer, J. lampocarpus
Name authority (Engelmann) Buchenau: Botanische Jahrbucher fur Systematik, Pflanzengeschichte und Pflanzengeographie 12: 268. (1890) Linnaeus: Sp. Pl. 1: 327. (1753)
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