OregonFlora: Juncus interior vs. Juncus laccatus

	Juncus interior	Juncus laccatus
	interior juncus	shiny rush
Habit	Plants perennial, (11)20–60 cm tall, cespitose, base usually pink, 4–6 strong stem ridges visible per side.	Plants perennial, 25–108 cm tall, cespitose, fresh stems shiny, smooth, dried fruiting stems slender, 0.6–2.6 mm diameter above distal sheath, remaining green, with 6–16 strong ridges becoming visible per side, dried ridges coarse or wide, capped with low dull cells.
Leaves	thin and wiry; blade flat and slightly inrolled; auricles soft, 2-textured, usually thicker proximally and more opaque than thin distal margin, 0.4–0.8(1.2)mm; dirty white to translucent; dull, rounded.	lacking blades; proximal sheaths smooth, not papillose (at 10×); distal sheaths 5–18 cm; distal half dark brown or black; shiny; thick and glossy; nerves obscure; apices symmetrical, unwinged, uniformly thick; dark, not inrolled.
Inflorescences	cymes, 1.5– 7 cm; bractlets subtending flowers acuminate to aristate.	loose clusters; branches usually visible; inflorescence bracts not swollen.
Flowers	tepals 6, light brown; tepal tips acuminate; stamens 6; filaments 0.8–1.1 mm; anthers 0.3–0.7(0.9) mm; styles 0.1–0.4(0.5)mm.	tepals 6; medium to dark brown-striped; stamens 3; filaments 0.4–0.9 mm; anthers 0.4–0.9 mm; styles 0.05–0.3 mm.
Capsules	3.3–4.7 mm; longer than the tepals, light brown; apex obtuse to truncate, not ridged or crested, 1-chambered.	1.7–2.2 mm; shorter than the tepals, brown to dark brown; apex obtuse to acute, 1-chambered.
Seeds	0.3–0.45 × 0.15–0.25 mm, apiculate.	0.4–0.6 × 0.2–0.25 mm, reticulate, apiculate.
2n	=80.	=40, 80.

	Juncus interior	Juncus laccatus
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion	River shores. 50–200 m. Col. CA, ID, WA; throughout North America. Native.	Shores, swales, springs, seasonally wet ground, peatlands, and ditches. 0–1600m. Casc, CR, Est, WV. CA, WA; north to British Columbia, southeast to Arizona. Native. Occasionally cultivated, the thick shiny dark and smooth sheath of this species is distinctive; J. exiguus has a thinner, paler, and more textured sheath; J. hesperius has a less shiny, paler, and papillose sheath.
Source	Flora of Oregon, volume 1, page 279 Peter Zika	Flora of Oregon, volume 1, page 279 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. 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. 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. gracilis
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, CA, OR, WA 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 laccatus

interior juncus

shiny rush

Habit

Plants perennial, (11)20–60 cm tall, cespitose, base usually pink, 4–6 strong stem ridges visible per side.

Plants perennial, 25–108 cm tall, cespitose, fresh stems shiny, smooth, dried fruiting stems slender, 0.6–2.6 mm diameter above distal sheath, remaining green, with 6–16 strong ridges becoming visible per side, dried ridges coarse or wide, capped with low dull cells.

Leaves

thin and wiry;

blade flat and slightly inrolled;

auricles soft, 2-textured, usually thicker proximally and more opaque than thin distal margin, 0.4–0.8(1.2)mm; dirty white to translucent; dull, rounded.

lacking blades;

proximal sheaths smooth, not papillose (at 10×);

distal sheaths 5–18 cm;

distal half dark brown or black; shiny; thick and glossy; nerves obscure;

apices symmetrical, unwinged, uniformly thick; dark, not inrolled.

Inflorescences

cymes, 1.5– 7 cm;

bractlets subtending flowers acuminate to aristate.

loose clusters;

branches usually visible;

inflorescence bracts not swollen.

Flowers

tepals 6, light brown;

tepal tips acuminate;

stamens 6;

filaments 0.8–1.1 mm;

anthers 0.3–0.7(0.9) mm;

styles 0.1–0.4(0.5)mm.

tepals 6; medium to dark brown-striped;

stamens 3;

filaments 0.4–0.9 mm;

anthers 0.4–0.9 mm;

styles 0.05–0.3 mm.

Capsules

3.3–4.7 mm; longer than the tepals, light brown;

apex obtuse to truncate, not ridged or crested, 1-chambered.

1.7–2.2 mm; shorter than the tepals, brown to dark brown;

apex obtuse to acute, 1-chambered.

Seeds

0.3–0.45 × 0.15–0.25 mm, apiculate.

0.4–0.6 × 0.2–0.25 mm, reticulate, apiculate.

=80.

=40, 80.

Juncus interior

Juncus laccatus

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

River shores. 50–200 m. Col. CA, ID, WA; throughout North America. Native.

Shores, swales, springs, seasonally wet ground, peatlands, and ditches. 0–1600m. Casc, CR, Est, WV. CA, WA; north to British Columbia, southeast to Arizona. Native.

Occasionally cultivated, the thick shiny dark and smooth sheath of this species is distinctive; J. exiguus has a thinner, paler, and more textured sheath; J. hesperius has a less shiny, paler, and papillose sheath.

Source

Flora of Oregon, volume 1, page 279
Peter Zika

Sibling taxa