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inch high dwarf rush, inch-high rush, twelfth rush

joint-leaf rush, jointed rush

Habit Herbs, annual, cespitose, 0.8–3.5 cm. Herbs, perennial, rhizomatous to nearly cespitose, 0.5–6(–10) dm.
Rhizomes

2–3 mm diam., not swollen.

Culms

to 70, more than 0.2 mm diam..

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

Cataphylls

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

Leaves

to 2.2 cm, 1/2–3/4 height of plant.

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

terminal solitary flowers;

bracts subtending inflorescence 1, widely truncate, enwrapping culm, inconspicuous, 0.25–0.9 mm, membranous, apex widely truncate, completely sheathing culm..

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

3-merous, : tepals erect to recurved at maturity, greenish or tinged red, 2–4 × 0.6–0.9 mm;

outer and inner series nearly equal, apex acutish;

stamens usually 3, filaments 0.9–1.6 mm, anthers 0.3–0.4 mm, 1/3 length of filaments;

style 0.1–0.3 mm, stigma 0.4–1.3 mm.

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

reddish to maroon, 3-locular, ovoid to ellipsoid, 1.8–3.2 × 1–2.5 mm, nearly equal or shorter than the tepals.

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

ovoid, 0.3–0.4 mm.

obovoid, 0.5 mm, not tailed.

n

= 16.

2n

= 80.

Juncus uncialis

Juncus articulatus

Phenology Flowering and fruiting spring–early summer. Fruiting mid summer–fall.
Habitat Margins of vernal pools and ponds Wet ground in ditches, lake and stream margins, and a variety of other habitats, often a calciphile
Elevation 0–1700 m (0–5600 ft) 0–3000 m (0–9800 ft)
Distribution
from FNA
CA; NV; OR
[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. Graminifolii 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. 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. 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. articulatus var. obtusatus, J. articulatus var. stolonifer, J. lampocarpus
Name authority Greene: Pittonia 2: 105. (1890) Linnaeus: Sp. Pl. 1: 327. (1753)
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