OregonFlora: Juncus canadensis vs. Juncus exiguus

	Juncus canadensis	Juncus exiguus
	Canada rush, Canadian rush	Klamath rush, weak rush
Habit	Plants perennial, 30–100 cm tall, cespitose.	Plants perennial, 40–90 cm tall, cespitose, fresh stems shiny (dull), green, smooth (with relatively inconspicuous ridges); dried fruiting stems slender, 0.7–1.5 mm diameter above distal sheath, often turning blue-green with 6–11(13) strong low ridges per side becoming visible; dried ridges coarse or wide, capped with low dull cells.
Leaves	basal and cauline; round; hollow, septate, 1–2 mm wide; auricles 1–1.2 mm.	lacking blades; proximal sheaths smooth (at 10×); distal sheaths 3–14 cm; distal half green to pale brown; thin; dull, not papillose; nerves prominent; apices symmetrical, unwinged; thin; dark and often slightly inrolled towards stem.
Inflorescences	panicles of 3–50 clusters; clusters 5–50-flowered, not obscured by inflorescence bract.	loose clusters; branches visible; inflorescence bracts not swollen; erect in fruit.
Flowers	tepals 6, green; reddish, or pale brown; tips acuminate; stamens 3; filaments 0.8–1.5 mm; anthers 0.3–0.5 mm; styles 0.2–0.3 mm.	tepals 6, usually mid to dark brown-striped; stamens 3; filaments 0.3–0.8 mm; anthers (0.3)0.4–0.8(0.9) mm; styles 0.2–0.3 mm.
Capsules	usually 0–1 mm longer than the tepals, dark brown, 1-chambered.	2.2–3 mm; shorter than or equaling the tepals; light to dark brown, 1-chambered.
Seeds	narrowly ellipsoid to linear, 1.25–1.9 × 0.2–0.25 mm; bodies 0.5– 0.8 mm; tails 0.3–0.5 mm, 0.5–1 times as long as seed body.	0.35–0.5 × 0.2–0.25 mm, reticulate, apiculate.
2n	=80.

	Juncus canadensis	Juncus exiguus
Distribution	[WildflowerSearch map] [BONAP county map]	[BONAP county map]
Discussion	Shores, ponds, peatlands, disturbed sandy acidic wet ground, cranberry farms, ditches. 0–100 m. Est. WA; north to British Columbia; eastern North America; Europe, New Zealand. Exotic. This species was introduced by cranberry agriculture and is spreading into natural wetlands. Some authors suggest rare flowers have 6 stamens.	Shores, wet meadows, marshes, stream banks, springs, peatlands. 900–2300m. CR, Sisk, Casc. CA; southeast to AZ. Native. The fresh upper stems of this species are variable, but are often smooth, green, and shiny. Upon drying they become blue-green and clearly ridged, so the plants look quite different in the field and in a herbarium. Similar Juncus hesperius is found at lower elevations and has papillose proximal sheaths; J. exiguus is montane and is never papillose.
Source	Flora of Oregon, volume 1, page 273 Peter Zika	Flora of Oregon, volume 1, page 277 Peter Zika
Sibling taxa	J. acuminatus, J. anthelatus, J. articulatus, J. balticus, J. bolanderi, J. brevicaudatus, J. breweri, J. bryoides, J. bufonius, J. bulbosus, J. capillaris, J. capitatus, J. compressus, J. confusus, J. conglomeratus, J. covillei, J. diffusissimus, J. drummondii, J. dudleyi, J. effusus, J. ensifolius, J. ensifolius x Juncus nevadensis, J. exiguus, J. falcatus, J. filiformis, J. gerardi, J. hemiendytus, J. hesperius, J. howellii, J. inflexus, J. interior, J. kelloggii, J. laccatus, J. lescurii, J. longistylis, J. marginatus, J. mertensianus, J. mexicanus, J. nevadensis, J. occidentalis, J. orthophyllus, J. oxymeris, J. parryi, J. patens, J. pelocarpus, J. planifolius, J. ranarius, J. regelii, J. saximontanus, J. supiniformis, J. tenuis, J. tiehmii, J. torreyi, J. triglumis, J. trilocularis, J. uncialis	J. acuminatus, J. anthelatus, J. articulatus, J. balticus, J. bolanderi, J. brevicaudatus, J. breweri, J. bryoides, J. bufonius, J. bulbosus, J. canadensis, J. capillaris, J. capitatus, J. compressus, J. confusus, J. conglomeratus, J. covillei, J. diffusissimus, J. drummondii, J. dudleyi, J. effusus, J. ensifolius, J. ensifolius x Juncus nevadensis, J. falcatus, J. filiformis, J. gerardi, J. hemiendytus, J. hesperius, J. howellii, J. inflexus, J. interior, J. kelloggii, J. laccatus, J. lescurii, J. longistylis, J. marginatus, J. mertensianus, J. mexicanus, J. nevadensis, J. occidentalis, J. orthophyllus, J. oxymeris, J. parryi, J. patens, J. pelocarpus, J. planifolius, J. ranarius, J. regelii, J. saximontanus, J. supiniformis, J. tenuis, J. tiehmii, J. torreyi, J. triglumis, J. trilocularis, J. uncialis
Synonyms		Juncus effusus var. exiguus
Web links	Local floras: BC, OR, WA Local Web sites: 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: CA, OR Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Juncus exiguus

Canada rush, Canadian rush

Klamath rush, weak rush

Habit

Plants perennial, 30–100 cm tall, cespitose.

Plants perennial, 40–90 cm tall, cespitose, fresh stems shiny (dull), green, smooth (with relatively inconspicuous ridges); dried fruiting stems slender, 0.7–1.5 mm diameter above distal sheath, often turning blue-green with 6–11(13) strong low ridges per side becoming visible; dried ridges coarse or wide, capped with low dull cells.

Leaves

basal and cauline; round; hollow, septate, 1–2 mm wide;

auricles 1–1.2 mm.

lacking blades;

proximal sheaths smooth (at 10×);

distal sheaths 3–14 cm;

distal half green to pale brown; thin; dull, not papillose; nerves prominent;

apices symmetrical, unwinged; thin; dark and often slightly inrolled towards stem.

Inflorescences

panicles of 3–50 clusters; clusters 5–50-flowered, not obscured by inflorescence bract.

loose clusters;

branches visible;

inflorescence bracts not swollen; erect in fruit.

Flowers

tepals 6, green; reddish, or pale brown;

tips acuminate;

stamens 3;

filaments 0.8–1.5 mm;

anthers 0.3–0.5 mm;

styles 0.2–0.3 mm.

tepals 6, usually mid to dark brown-striped;

stamens 3;

filaments 0.3–0.8 mm;

anthers (0.3)0.4–0.8(0.9) mm;

styles 0.2–0.3 mm.

Capsules

usually 0–1 mm longer than the tepals, dark brown, 1-chambered.

2.2–3 mm; shorter than or equaling the tepals; light to dark brown, 1-chambered.

Seeds

narrowly ellipsoid to linear, 1.25–1.9 × 0.2–0.25 mm;

bodies 0.5– 0.8 mm; tails 0.3–0.5 mm, 0.5–1 times as long as seed body.

0.35–0.5 × 0.2–0.25 mm, reticulate, apiculate.

=80.

Juncus canadensis

Juncus exiguus

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Shores, ponds, peatlands, disturbed sandy acidic wet ground, cranberry farms, ditches. 0–100 m. Est. WA; north to British Columbia; eastern North America; Europe, New Zealand. Exotic.

This species was introduced by cranberry agriculture and is spreading into natural wetlands. Some authors suggest rare flowers have 6 stamens.

Shores, wet meadows, marshes, stream banks, springs, peatlands. 900–2300m. CR, Sisk, Casc. CA; southeast to AZ. Native.

The fresh upper stems of this species are variable, but are often smooth, green, and shiny. Upon drying they become blue-green and clearly ridged, so the plants look quite different in the field and in a herbarium. Similar Juncus hesperius is found at lower elevations and has papillose proximal sheaths; J. exiguus is montane and is never papillose.

Source

Flora of Oregon, volume 1, page 273
Peter Zika

Flora of Oregon, volume 1, page 277
Peter Zika

Sibling taxa