OregonFlora: Juncus effusus vs. Juncus arcticus

	Juncus effusus	Juncus breweri (synonym of Juncus arcticus)
	pasture rush, soft rush	Brewer's rush, salt rush
Habit	Plants perennial, 50–150 cm tall, cespitose; fruiting stems stout, usually 2–4.9 mm diameter above distal sheath; fresh upper stems shiny, smooth, dried stems with (12)18–26(32) weak low ridges, slender and relatively inconspicuous, visible on one side when dried, dried ridges capped with low dull cells (at 10×).	Plants perennial, 20–140 cm tall, rhizomatous, stems usually flattened, often arching, twisted, without strong ridges visible fresh or dried.
Leaves	lacking blades; distal sheaths dull or shiny; smooth or papillose; apex symmetrical or asymmetrical; thin or thickened, winged or not.	lacking blades; older distal sheaths 2–13 cm, dark brown; shiny; apex usually symmetrical; thin.
Inflorescences	dense or open; inflorescence bracts not swollen; erect in fruit.	dense head-like clusters of 10–20 flowers; branches obscured.
Flowers	tepals 6, usually green to pale brown (dark brown-striped); stamens 3; filaments 0.4–0.7 mm; anthers 0.4–0.7 mm; styles 0–0.4 mm.	tepals 6, usually 6–8 mm, dark brown- or black-striped; stamens 6; filaments 0.4–0.7 mm; anthers 1.6–2.8 mm; styles 0.7–1.4 mm.
Capsules	1.6–2.5 mm; shorter than the tepals; light to dark brown; apices obtuse to acute (notched), 1-chambered.	3–5 mm; shorter than or equaling the tepals, dark brown; apex obtuse to acute, 3-chambered.
Seeds	0.4–0.5 × 0.2 mm, reticulate, apiculate.	0.7–1.1 × 0.4–0.6 mm, not apiculate.

	Juncus effusus	Juncus breweri
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion	The various subspecies include two introductions that often grow mingled with our native plants; the species can dominate wet pastures with heavy grazing. 9 subspecies; 3 subspecies in Oregon.	Dunes, sandy swales, sandy ditches. 0–50 m. Est. CA, WA, north to British Columbia. Native. The little-known Juncus lescurii may represent a series of fertile hybrids between J. balticus and J. breweri and is intermediate in inflorescence characters. Juncus breweri has a denser and more nearly globose inflorescence than the other two taxa, with its inflorescence branches obscured by the compact arrangement of flowers or capsules.
Source	Flora of Oregon, volume 1, page 276 Peter Zika	Flora of Oregon, volume 1, page 272 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. canadensis, J. capillaris, J. capitatus, J. compressus, J. confusus, J. conglomeratus, J. covillei, J. diffusissimus, J. drummondii, J. dudleyi, 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. 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
Subordinate taxa	J. effusus ssp. effusus, J. effusus ssp. pacificus, J. effusus ssp. solutus
Synonyms		Juncus arcticus, Juncus arcticus var. balticus
Web links	Local floras: BC, CA, OR, WA 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 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

Juncus breweri

(synonym of Juncus arcticus)

pasture rush, soft rush

Brewer's rush, salt rush

Habit

Plants perennial, 50–150 cm tall, cespitose; fruiting stems stout, usually 2–4.9 mm diameter above distal sheath; fresh upper stems shiny, smooth, dried stems with (12)18–26(32) weak low ridges, slender and relatively inconspicuous, visible on one side when dried, dried ridges capped with low dull cells (at 10×).

Plants perennial, 20–140 cm tall, rhizomatous, stems usually flattened, often arching, twisted, without strong ridges visible fresh or dried.

Leaves

lacking blades;

distal sheaths dull or shiny; smooth or papillose;

apex symmetrical or asymmetrical; thin or thickened, winged or not.

lacking blades; older distal sheaths 2–13 cm, dark brown; shiny;

apex usually symmetrical; thin.

Inflorescences

dense or open;

inflorescence bracts not swollen; erect in fruit.

dense head-like clusters of 10–20 flowers;

branches obscured.

Flowers

tepals 6, usually green to pale brown (dark brown-striped);

stamens 3;

filaments 0.4–0.7 mm;

anthers 0.4–0.7 mm;

styles 0–0.4 mm.

tepals 6, usually 6–8 mm, dark brown- or black-striped;

stamens 6;

filaments 0.4–0.7 mm;

anthers 1.6–2.8 mm;

styles 0.7–1.4 mm.

Capsules

1.6–2.5 mm; shorter than the tepals; light to dark brown;

apices obtuse to acute (notched), 1-chambered.

3–5 mm; shorter than or equaling the tepals, dark brown;

apex obtuse to acute, 3-chambered.

Seeds

0.4–0.5 × 0.2 mm, reticulate, apiculate.

0.7–1.1 × 0.4–0.6 mm, not apiculate.

Juncus effusus

Juncus breweri

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

The various subspecies include two introductions that often grow mingled with our native plants; the species can dominate wet pastures with heavy grazing. 9 subspecies; 3 subspecies in Oregon.

Dunes, sandy swales, sandy ditches. 0–50 m. Est. CA, WA, north to British Columbia. Native.

The little-known Juncus lescurii may represent a series of fertile hybrids between J. balticus and J. breweri and is intermediate in inflorescence characters. Juncus breweri has a denser and more nearly globose inflorescence than the other two taxa, with its inflorescence branches obscured by the compact arrangement of flowers or capsules.

Source

Flora of Oregon, volume 1, page 276
Peter Zika

Flora of Oregon, volume 1, page 272
Peter Zika

Sibling taxa