FNA: Juncus dubius vs. Juncus nodosus

	Juncus dubius	Juncus nodosus
	dubius rush, mariposa rush, questionable rush	jointed rush, knotted rish, knotted rush, tuberous rush
Habit	Herbs, perennial, rhizomatous, 3–7.5 dm.	Herbs, perennial, rhizomatous, 0.4–5.5(–7) dm.
Rhizomes	2–3 mm diam., not swollen.	with swollen nodes, 1 mm diam.
Culms	erect, terete, 2–4 mm diam., smooth or rugulose.	erect, terete, 1–3 mm diam., smooth.
Cataphylls	1–2, pink to straw-colored, apex acute.	0 or 1–2., pink to gray, apex acute.
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, cauline 2–4, green to pink; auricles 0.5–1.7 mm, apex rounded, membranaceous to cartilaginous; blade terete, 6–30 cm × 0.5–1.5 mm.
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.	terminal racemes of 3–15 heads, 0.6–6 cm, branches ascending to erect; primary bract erect; heads 6–30-flowered, spheric, 6–10(–12) mm diam.
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.	tepals green to light brown, lance-subulate, 2.4–4.1 mm, nearly equal, apex acuminate; stamens 3 or 6, anthers 1/2 to equal filament length.
Capsules	exserted, chestnut brown, 1-locular, subuloidsubulate, (2.4–)3–3.9 mm, apex tapering to subulate tip, valves separating at dehiscence.	exserted, chestnut brown, 1-locular, lance-subulate, 3.2–5 mm, apex tapering, valves separating at dehiscence, fertile throughout or only proximal to middle.
Seeds	obovoid, 0.3–0.4 mm, not tailed.	oblong, ellipsoid, or obovoid, 0.4–0.5 mm, not tailed.
2n	= 40.	= 40.

	Juncus dubius	Juncus nodosus
Phenology	Fruiting early summer–late fall.	Fruiting early summer–fall.
Habitat	Montane meadows, riverbeds, canyons, aroyos	Sandy and muddy shores of lakes, streams, rivers, and estuaries (both freshwater and brackish), swamps, fens, salt marshes, and wet fields, often calcareous
Elevation	100–1600 m (300–5200 ft)	0–2200 m (0–7200 ft)
Distribution	CA [WildflowerSearch map] [BONAP county map]	AK; AZ; CA; CO; CT; DE; IA; ID; IL; IN; KS; MA; MD; ME; MI; MN; MO; MT; ND; NE; NH; NJ; NM; NV; NY; OH; OK; PA; RI; SD; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; NT; ON; PE; QC; SK; YT; Mexico (s to Puebla) [WildflowerSearch map] [BONAP county 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.)	The Texas populations and some of the northern Mexican populations consistantly have 3 stamens. These populations have been separated as Juncus nodosus var. meridionalis. Plants with 3 stamens are found elsewhere, however, and other significant characters do not appear to separate these populations. (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. 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. 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. 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. nodosus var. meridionalis, J. rostkovii
Name authority	Engelmann	Linnaeus: Sp. Pl., ed. 2 1: 466. (1762)
Web links	Local floras: CA, OR Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: BC, CA, WA Local Web sites: CalFlora, CalPhotos, Flora NW, Go Botany, IL Wildflowers, KS Wildflowers, MD Biodiversity, MI Flora, MN Wildflowers, MO Plants, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Juncus nodosus

dubius rush, mariposa rush, questionable rush

jointed rush, knotted rish, knotted rush, tuberous rush

Habit

Herbs, perennial, rhizomatous, 3–7.5 dm.

Herbs, perennial, rhizomatous, 0.4–5.5(–7) dm.

Rhizomes

2–3 mm diam., not swollen.

with swollen nodes, 1 mm diam.

Culms

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

erect, terete, 1–3 mm diam., smooth.

Cataphylls

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

0 or 1–2., pink to gray, apex acute.

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, cauline 2–4, green to pink;

auricles 0.5–1.7 mm, apex rounded, membranaceous to cartilaginous;

blade terete, 6–30 cm × 0.5–1.5 mm.

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.

terminal racemes of 3–15 heads, 0.6–6 cm, branches ascending to erect;

primary bract erect;

heads 6–30-flowered, spheric, 6–10(–12) mm diam.

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.

tepals green to light brown, lance-subulate, 2.4–4.1 mm, nearly equal, apex acuminate;

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

Capsules

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

exserted, chestnut brown, 1-locular, lance-subulate, 3.2–5 mm, apex tapering, valves separating at dehiscence, fertile throughout or only proximal to middle.

Seeds

obovoid, 0.3–0.4 mm, not tailed.

oblong, ellipsoid, or obovoid, 0.4–0.5 mm, not tailed.

= 40.

Juncus nodosus

Phenology

Fruiting early summer–late fall.

Fruiting early summer–fall.

Habitat

Montane meadows, riverbeds, canyons, aroyos

Sandy and muddy shores of lakes, streams, rivers, and estuaries (both freshwater and brackish), swamps, fens, salt marshes, and wet fields, often calcareous

Elevation

100–1600 m (300–5200 ft)

0–2200 m (0–7200 ft)

Distribution

[WildflowerSearch map]

[BONAP county map]

AK; AZ; CA; CO; CT; DE; IA; ID; IL; IN; KS; MA; MD; ME; MI; MN; MO; MT; ND; NE; NH; NJ; NM; NV; NY; OH; OK; PA; RI; SD; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; NT; ON; PE; QC; SK; YT; Mexico (s to Puebla)

[WildflowerSearch map]

[BONAP county 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.)

The Texas populations and some of the northern Mexican populations consistantly have 3 stamens. These populations have been separated as Juncus nodosus var. meridionalis. Plants with 3 stamens are found elsewhere, however, and other significant characters do not appear to separate these populations.

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

Source

FNA vol. 22.

Parent taxa

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. 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. 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. 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. nodosus var. meridionalis, J. rostkovii

Name authority

Engelmann

Linnaeus: Sp. Pl., ed. 2 1: 466. (1762)

Web links

Local floras: CA, OR
Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria
WildflowerSearch
iNaturalist (observations)
USDA Plants Database
LBJ Wildflower Center
SEINet
Plants of the World Online
Encyclopedia of Life
Wikipedia
Google Image Search

Local floras: BC, CA, WA
Local Web sites: CalFlora, CalPhotos, Flora NW, Go Botany, IL Wildflowers, KS Wildflowers, MD Biodiversity, MI Flora, MN Wildflowers, MO Plants, PNW Herbaria
WildflowerSearch
iNaturalist (observations)
USDA Plants Database
LBJ Wildflower Center
SEINet
Plants of the World Online
Encyclopedia of Life
Wikipedia
Google Image Search

Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).

Choose a data source: Flora of North America, OregonFlora, UW Burke Herbarium

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Flora of North America species comparison

Juncus dubius

Juncus nodosus

Juncus dubius

Juncus nodosus