FNA: Juncus debilis vs. Juncus canadensis

	Juncus debilis	Juncus canadensis
	weak rush	Canada rush, Canadian rush
Habit	Herbs, perennial, cespitose, 1–2.5 dm.	Herbs, perennial, cespitose, 3–10 dm.
Culms	erect, terete, 1–2 mm diam., smooth.	erect, 1–5 mm diam., smooth.
Cataphylls	0–1, maroon or dark green, apex acute.	0 or 1–2, straw-colored, apex rounded.
Leaves	basal 0–1, cauline 1–3; auricles 1–1.5 mm, apex rounded, scarious; blade maroon or dark green, terete, 1–12.5 cm × 0.5–1.5 mm.	basal 1, cauline 2–3; auricles 1–1.2 mm, apex rounded, scarious; blade terete, 7–22 cm × 1.2–3 mm.
Inflorescences	terminal panicles of 3–50 heads, 2–8 cm, branches ascending to spreading; primary bract erect; heads 2–10-flowered, obpyramidal, 2–5 mm diam.	panicles or racemes of 3–50 heads, 2–20 cm, branches erect to ascending; primary bract erect; heads 5–50-flowered, obconic to spheric, 3–10 mm diam.
Flowers	tepals green to straw-colored, lanceolate, 1.8–2.3(–2.5) mm, apex sharply acuminate; stamens 3, 1/2 filament length.	tepals green or straw-colored to reddish brown, lanceolate; outer tepals 2.7–3.8 mm, apex acuminate; inner tepals 2.9–4 mm, apex acuminate; stamens 3(–6), anthers 1/2 filament length.
Capsules	exserted, straw-colored, 1-locular, narrowly ellipsoid to lanceoloid, 2.8–3.7 7(–4.2) mm, apex acute, valves separating at dehiscence.	equaling perianth or exserted, chestnut brown, imperfectly 3-locular, lanceoloid, 3.3–4.5 mm, acute proximal to beak, valves separating at dehiscence.
Seeds	ellipsoid, 0.3–0.4 mm, not tailed; body clear yellow-brown.	fusiform, 1.1–1.9 mm, tailed; body covered with whitish translucent veil.
2n		= 80.

	Juncus debilis	Juncus canadensis
Phenology	Fruiting summer.	Fruiting mid summer–fall.
Habitat	Marshy shores, in small streams, swamps, wet clearings, spring runs, commonly in very soft mucky substrates	Salt, brackish, and calcareous marshes, acid bogs, roadsides, tidal flats, swamps, patterned fen, lake shores, beaches
Elevation	0–700 m (0–2300 ft)	0–200 m (0–700 ft)
Distribution	AL; AR; DE; FL; GA; IL; KY; LA; MD; MO; MS; NC; NJ; NY; PA; SC; TN; TX; VA; Mexicos (Chiapas); Central America (Honduras) [WildflowerSearch map] [BONAP county map]	AL; AR; CT; DC; DE; FL; GA; IA; IL; IN; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NE; NH; NJ; NY; OH; OR; PA; RI; SC; SD; TN; VA; VT; WI; WV; MB; NB; NF; NS; ON; PE; QC; SPM [WildflowerSearch map] [BONAP county map]
Discussion	Juncus debilis A. Gray is a name being proposed for conservation. (Discussion copyrighted by Flora of North America; reprinted with permission.)	Two varieties and two forms occurring within the flora have been recognized (M. L. Fernald 1945b). Juncus canadensis var. sparsiflorus has stiffly erect inflorescence branches, and the flowers are generally longer than those of var. canadensis. These varieties simply serve to give name to parts of the broad morphologic range of variation encountered in J. canadensis and do not appear to represent any distinct biological entities. Juncus canadensis and the following three species form a distinctive group: they have ve been variously treated as speecies (as here), varieties of J. canadensis, or as two species, J. canadensis and a polymorphic species, J. brachysephalus, encompassing the other three species (B. Boivin 1967–1979, part IV). Most of the species are easily recognized at their extremes but show a fair amount of overlap. (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. 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. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, J. brachycephalus, J. brachyphyllus, J. brevicaudatus, J. bryoides, J. bufonius, J. bulbosus, J. caesariensis, 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. acuminatus var. debilis, J. radicans	J. canadensis var. longicaudatus, J. canadensis var. sparsiflorus, J. longicaudatus, J. polycephalus var. paradoxus
Name authority	A. Gray: Manual 481506. (1848)	J. Gay ex Laharpe: in J. J. C. de Laharpe, Essai Monogr. Jonc. 46. (1825)
Web links	Local Web sites: IL Wildflowers, LA Plants, MD Biodiversity, MO Plants 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, OR, WA Local Web sites: Flora NW, Go Botany, IL Wildflowers, LA Plants, 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 canadensis

weak rush

Canada rush, Canadian rush

Habit

Herbs, perennial, cespitose, 1–2.5 dm.

Herbs, perennial, cespitose, 3–10 dm.

Culms

erect, terete, 1–2 mm diam., smooth.

erect, 1–5 mm diam., smooth.

Cataphylls

0–1, maroon or dark green, apex acute.

0 or 1–2, straw-colored, apex rounded.

Leaves

basal 0–1, cauline 1–3;

auricles 1–1.5 mm, apex rounded, scarious;

blade maroon or dark green, terete, 1–12.5 cm × 0.5–1.5 mm.

basal 1, cauline 2–3;

auricles 1–1.2 mm, apex rounded, scarious;

blade terete, 7–22 cm × 1.2–3 mm.

Inflorescences

terminal panicles of 3–50 heads, 2–8 cm, branches ascending to spreading;

primary bract erect;

heads 2–10-flowered, obpyramidal, 2–5 mm diam.

panicles or racemes of 3–50 heads, 2–20 cm, branches erect to ascending;

primary bract erect;

heads 5–50-flowered, obconic to spheric, 3–10 mm diam.

Flowers

tepals green to straw-colored, lanceolate, 1.8–2.3(–2.5) mm, apex sharply acuminate;

stamens 3, 1/2 filament length.

tepals green or straw-colored to reddish brown, lanceolate;

outer tepals 2.7–3.8 mm, apex acuminate;

inner tepals 2.9–4 mm, apex acuminate;

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

Capsules

exserted, straw-colored, 1-locular, narrowly ellipsoid to lanceoloid, 2.8–3.7 7(–4.2) mm, apex acute, valves separating at dehiscence.

equaling perianth or exserted, chestnut brown, imperfectly 3-locular, lanceoloid, 3.3–4.5 mm, acute proximal to beak, valves separating at dehiscence.

Seeds

ellipsoid, 0.3–0.4 mm, not tailed;

body clear yellow-brown.

fusiform, 1.1–1.9 mm, tailed;

body covered with whitish translucent veil.

= 80.

Juncus canadensis

Phenology

Fruiting summer.

Fruiting mid summer–fall.

Habitat

Marshy shores, in small streams, swamps, wet clearings, spring runs, commonly in very soft mucky substrates

Salt, brackish, and calcareous marshes, acid bogs, roadsides, tidal flats, swamps, patterned fen, lake shores, beaches

Elevation

0–700 m (0–2300 ft)

0–200 m (0–700 ft)

Distribution

AL; AR; DE; FL; GA; IL; KY; LA; MD; MO; MS; NC; NJ; NY; PA; SC; TN; TX; VA; Mexicos (Chiapas); Central America (Honduras)

[WildflowerSearch map]

[BONAP county map]

AL; AR; CT; DC; DE; FL; GA; IA; IL; IN; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NE; NH; NJ; NY; OH; OR; PA; RI; SC; SD; TN; VA; VT; WI; WV; MB; NB; NF; NS; ON; PE; QC; SPM

[WildflowerSearch map]

[BONAP county map]

Discussion

Juncus debilis A. Gray is a name being proposed for conservation.

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

Two varieties and two forms occurring within the flora have been recognized (M. L. Fernald 1945b). Juncus canadensis var. sparsiflorus has stiffly erect inflorescence branches, and the flowers are generally longer than those of var. canadensis. These varieties simply serve to give name to parts of the broad morphologic range of variation encountered in J. canadensis and do not appear to represent any distinct biological entities.

Juncus canadensis and the following three species form a distinctive group: they have ve been variously treated as speecies (as here), varieties of J. canadensis, or as two species, J. canadensis and a polymorphic species, J. brachysephalus, encompassing the other three species (B. Boivin 1967–1979, part IV). Most of the species are easily recognized at their extremes but show a fair amount of overlap.

(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. 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. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, J. brachycephalus, J. brachyphyllus, J. brevicaudatus, J. bryoides, J. bufonius, J. bulbosus, J. caesariensis, 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. acuminatus var. debilis, J. radicans

J. canadensis var. longicaudatus, J. canadensis var. sparsiflorus, J. longicaudatus, J. polycephalus var. paradoxus

Name authority

A. Gray: Manual 481506. (1848)

J. Gay ex Laharpe: in J. J. C. de Laharpe, Essai Monogr. Jonc. 46. (1825)

Web links

Local Web sites: IL Wildflowers, LA Plants, MD Biodiversity, MO Plants
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, OR, WA
Local Web sites: Flora NW, Go Botany, IL Wildflowers, LA Plants, 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 debilis

Juncus canadensis

Juncus debilis

Juncus canadensis