OregonFlora: Juncus tenuis vs. Juncus canadensis

	Juncus tenuis	Juncus canadensis
	path rush, poverty rush, slender rush	Canada rush, Canadian rush
Habit	Plants perennial, 15–50 cm tall, cespitose, usually delicate, base usually green to brown, with 0–1(2) strong longitudinal stem ridges visible on a side.	Plants perennial, 30–100 cm tall, cespitose.
Leaves	thin and wiry; blade flat and slightly inrolled, usually 1–8 mm on early season shoots; dirty white or translucent, scarious; acute or acuminate; auricles soft and thin.	basal and cauline; round; hollow, septate, 1–2 mm wide; auricles 1–1.2 mm.
Inflorescences	cymes, usually small, 1–6 cm; individual flowers often longer than internodes; bractlets subtending flowers usually acute (blunt).	panicles of 3–50 clusters; clusters 5–50-flowered, not obscured by inflorescence bract.
Flowers	tepals 6, 3–4.1 mm, green to reddish; tips acuminate; stamens 6; filaments 0.6–1.2 mm; anthers usually 0.4–0.6(0.8)mm; styles 0.1–0.3(0.5)mm.	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.
Capsules	usually 2.5–3 mm; more than 75% the length of; and shorter than the tepals, pale brown; apex usually blunt (acute), not crested, 1-chambered.	usually 0–1 mm longer than the tepals, dark brown, 1-chambered.
Seeds	0.4–0.5 × 0.2–0.25 mm, apiculate.	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.
2n	=40, 80.	=80.

	Juncus tenuis	Juncus canadensis
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion	Shores, swales, springs, dune hollows, wet woods, marshes, damp paths, ditches, cranberry farms, moist disturbed sites. 0–1800m. BW, Casc, CR, Est, Lava, Sisk, WV. CA, NV, ID, WA; throughout most of North America. Native. Juncus tenuis is usually much smaller than Juncus anthelatus. The blunt unridged capsules separate J. tenuis from J. confusus, J. occidentalis, and J. trilocularis.	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.
Source	Flora of Oregon, volume 1, page 284 Peter Zika	Flora of Oregon, volume 1, page 273 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. 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. 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
Synonyms	Juncus tenuis var. tenuis
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, 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

Juncus canadensis

path rush, poverty rush, slender rush

Canada rush, Canadian rush

Habit

Plants perennial, 15–50 cm tall, cespitose, usually delicate, base usually green to brown, with 0–1(2) strong longitudinal stem ridges visible on a side.

Plants perennial, 30–100 cm tall, cespitose.

Leaves

thin and wiry;

blade flat and slightly inrolled, usually 1–8 mm on early season shoots; dirty white or translucent, scarious; acute or acuminate;

auricles soft and thin.

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

auricles 1–1.2 mm.

Inflorescences

cymes, usually small, 1–6 cm; individual flowers often longer than internodes;

bractlets subtending flowers usually acute (blunt).

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

Flowers

tepals 6, 3–4.1 mm, green to reddish;

tips acuminate;

stamens 6;

filaments 0.6–1.2 mm;

anthers usually 0.4–0.6(0.8)mm;

styles 0.1–0.3(0.5)mm.

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.

Capsules

usually 2.5–3 mm; more than 75% the length of; and shorter than the tepals, pale brown;

apex usually blunt (acute), not crested, 1-chambered.

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

Seeds

0.4–0.5 × 0.2–0.25 mm, apiculate.

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.

=40, 80.

=80.

Juncus canadensis

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

Shores, swales, springs, dune hollows, wet woods, marshes, damp paths, ditches, cranberry farms, moist disturbed sites. 0–1800m. BW, Casc, CR, Est, Lava, Sisk, WV. CA, NV, ID, WA; throughout most of North America. Native.

Juncus tenuis is usually much smaller than Juncus anthelatus. The blunt unridged capsules separate J. tenuis from J. confusus, J. occidentalis, and J. trilocularis.

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.

Source

Flora of Oregon, volume 1, page 284
Peter Zika

Flora of Oregon, volume 1, page 273
Peter Zika

Sibling taxa