OregonFlora: Juncus ensifolius vs. Juncus exiguus

	Juncus ensifolius	Juncus exiguus
	dagger-leaved rush, swordleaf rush	Klamath rush, weak rush
Habit	Plants perennial, 15–65 cm tall, rhizomatous.	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	flat; iris-like, blue-green, partially septate; auricles usually absent (0.1–0.4 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	1–12(22) clusters; clusters often head-like, 3–70-flowered.	loose clusters; branches visible; inflorescence bracts not swollen; erect in fruit.
Flowers	tepals 6, brown to often dark brown or black; stamens 3; filaments 0.6–1.1 mm; anthers 0.4–0.7 mm; styles 0.2–0.8(1) 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	longer than or equaling tepals, dark brown to blackish; apices obtuse or acute and abruptly tapered to short beak, 1-chambered.	2.2–3 mm; shorter than or equaling the tepals; light to dark brown, 1-chambered.
Seeds	0.4–0.5(0.6) × 0.15–0.2 mm, apiculate, reticulate.	0.35–0.5 × 0.2–0.25 mm, reticulate, apiculate.

	Juncus ensifolius	Juncus exiguus
Distribution	[WildflowerSearch map] [BONAP county map]	[BONAP county map]
Discussion	Shores, swales, springs, wet meadows, wet prairie, damp dunes, peatlands, ditches. 0–2500m. Throughout Oregon. CA, ID, NV, WA; north to Alaska, east to Saskatchewan, SD and CO, south to AZ and Mexico; Ontario and Quebec south to WI and NY; HI; northeastern Asia, Europe, New Zealand. Native. With three stamens, this species is reliably separated from J. saximontanus, which has six stamens. Rare plants with variable stamen numbers in an inflorescence may represent hybrids and need investigation.	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 277 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. canadensis, J. capillaris, J. capitatus, J. compressus, J. confusus, J. conglomeratus, J. covillei, J. diffusissimus, J. drummondii, J. dudleyi, J. effusus, 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 ensifolius var. ensifolius, Juncus tracyi	Juncus effusus var. exiguus
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: 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

dagger-leaved rush, swordleaf rush

Klamath rush, weak rush

Habit

Plants perennial, 15–65 cm tall, rhizomatous.

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

flat; iris-like, blue-green, partially septate;

auricles usually absent (0.1–0.4 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

1–12(22) clusters; clusters often head-like, 3–70-flowered.

loose clusters;

branches visible;

inflorescence bracts not swollen; erect in fruit.

Flowers

tepals 6, brown to often dark brown or black;

stamens 3;

filaments 0.6–1.1 mm;

anthers 0.4–0.7 mm;

styles 0.2–0.8(1) 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

longer than or equaling tepals, dark brown to blackish;

apices obtuse or acute and abruptly tapered to short beak, 1-chambered.

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

Seeds

0.4–0.5(0.6) × 0.15–0.2 mm, apiculate, reticulate.

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

Juncus ensifolius

Juncus exiguus

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Shores, swales, springs, wet meadows, wet prairie, damp dunes, peatlands, ditches. 0–2500m. Throughout Oregon. CA, ID, NV, WA; north to Alaska, east to Saskatchewan, SD and CO, south to AZ and Mexico; Ontario and Quebec south to WI and NY; HI; northeastern Asia, Europe, New Zealand. Native.

With three stamens, this species is reliably separated from J. saximontanus, which has six stamens. Rare plants with variable stamen numbers in an inflorescence may represent hybrids and need investigation.

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 277
Peter Zika

Sibling taxa