OregonFlora: Juncus trilocularis vs. Juncus effusus

	Juncus trilocularis	Juncus effusus
	foothill rush	pasture rush, soft rush
Habit	Plants perennial, 10–78 cm tall, cespitose, lacking strong stem ridges.	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×).
Leaves	thin and wiry; blade flat and slightly inrolled; auricles soft and thin distally, 0.3–3 mm; dull, rounded or acute; dirty white.	lacking blades; distal sheaths dull or shiny; smooth or papillose; apex symmetrical or asymmetrical; thin or thickened, winged or not.
Inflorescences	cymes, 2–20 cm, usually open; bractlets subtending flowers acute to acuminate, often aristate.	dense or open; inflorescence bracts not swollen; erect in fruit.
Flowers	tepals 6, 3.3–5.1 mm; greenish to pale brown, nearly concolorous; tips acuminate; outer tepals distinctly longer than inner tepals; stamens 6; filaments 0.5–0.8 mm; anthers (0.6)0.8–1.7 mm; styles 0.3–1 mm.	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.
Capsules	2.8–4.1 mm; shorter than the tepals, pale brown to dark brown; apex truncate to notched (acute), crested, 3-chambered.	1.6–2.5 mm; shorter than the tepals; light to dark brown; apices obtuse to acute (notched), 1-chambered.
Seeds	0.4–0.6 × 0.2–0.3 mm, apiculate, reticulate.	0.4–0.5 × 0.2 mm, reticulate, apiculate.

	Juncus trilocularis	Juncus effusus
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion	Seasonally damp meadows, springs, shores, creek banks, moist open forest, ditches. 300–1900m. BW, Col, ECas, Owy, Sisk, Casc. CA, ID, NV, WA. Native. This is an uncommon species found east of the Cascade Range and in the Siskiyou Mountains that has long been confused with Juncus brachyphyllus, a plant of grasslands and glades in the Midwest, which occurs no further west than Nebraska.	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.
Source	Flora of Oregon, volume 1, page 284 Peter Zika	Flora of Oregon, volume 1, page 276 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. 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. 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. 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 brachyphyllus
Web links	Local floras: 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, 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

Juncus effusus

foothill rush

pasture rush, soft rush

Habit

Plants perennial, 10–78 cm tall, cespitose, lacking strong stem ridges.

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×).

Leaves

thin and wiry;

blade flat and slightly inrolled;

auricles soft and thin distally, 0.3–3 mm; dull, rounded or acute; dirty white.

lacking blades;

distal sheaths dull or shiny; smooth or papillose;

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

Inflorescences

cymes, 2–20 cm, usually open;

bractlets subtending flowers acute to acuminate, often aristate.

dense or open;

inflorescence bracts not swollen; erect in fruit.

Flowers

tepals 6, 3.3–5.1 mm; greenish to pale brown, nearly concolorous;

tips acuminate;

outer tepals distinctly longer than inner tepals;

stamens 6;

filaments 0.5–0.8 mm;

anthers (0.6)0.8–1.7 mm;

styles 0.3–1 mm.

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.

Capsules

2.8–4.1 mm; shorter than the tepals, pale brown to dark brown;

apex truncate to notched (acute), crested, 3-chambered.

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

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

Seeds

0.4–0.6 × 0.2–0.3 mm, apiculate, reticulate.

0.4–0.5 × 0.2 mm, reticulate, apiculate.

Juncus trilocularis

Juncus effusus

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

Seasonally damp meadows, springs, shores, creek banks, moist open forest, ditches. 300–1900m. BW, Col, ECas, Owy, Sisk, Casc. CA, ID, NV, WA. Native.

This is an uncommon species found east of the Cascade Range and in the Siskiyou Mountains that has long been confused with Juncus brachyphyllus, a plant of grasslands and glades in the Midwest, which occurs no further west than Nebraska.

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.

Source

Flora of Oregon, volume 1, page 284
Peter Zika

Flora of Oregon, volume 1, page 276
Peter Zika

Sibling taxa