FNA: Juncus acutus vs. Juncus interior

	Juncus acutus	Juncus interior
	sharp rush, spiny rush	inland rush, interior juncus, interior rush
Habit		Herbs, perennial, tufted, 2–6 dm.
Rhizomes		densely branching.
Culms		1–10.
Cataphylls		1–3.
Leaves		basal, 1–2(–3); auricles whitish or purplish tinged, 0.2–0.4(–0.6) mm, scarious; blade flat, 5–15 cm × 0.5–1.1 mm, margins entire.
Inflorescences		usually somewhat compact, 1.5–7 cm; primary bract usually shorter than inflorescence.
Flowers		bracteoles 2; tepals greenish, lanceolate, 3.3–4.4 mm, apex acuminate; stamens 6, filaments 0.5–0.9 mm, anthers 0.4–0.6 mm; style 0.1–0.2 mm.
Capsules		light tan or darker, 1-locular to pseudo-3-locular, ellipsoid to nearly globose, (3.3–)3.8–4.7 mm, nearly equal to or longer than tepals.
Seeds		tan, ellipsoid to lunate, 0.436–0.73 mm, not tailed.
2n		= 80.

	Juncus acutus	Juncus interior
Phenology		Flowering and fruiting late spring–early summer.
Habitat		Dry, often upland sites in prairies, exposed disturbed sites, and ditches in sandy or clayey soils
Distribution	AZ; CA; NV; South America; Mexico (Baja Calif); South Africa; Atlantic Islands [WildflowerSearch map] [BONAP county map]	AR; AZ; CO; IA; IL; IN; KS; KY; LA; MN; MO; MT; ND; NE; NM; OH; OK; SD; TN; UT; WI; WY; AB; MB; ON; QC; SK; Texas [WildflowerSearch map] [BONAP county map]
Discussion	Subspecies 2 (1 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.)
Source	FNA vol. 22, p. 237.	FNA vol. 22.
Parent taxa	Juncaceae > Juncus > subg. Juncus	Juncaceae > Juncus > subg. Poiophylli
Sibling taxa	J. acuminatus, J. acutiflorus, J. alpinoarticulatus, J. anthelatus, J. arcticus, J. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, J. brachycephalus, J. brachyphyllus, J. brevicaudatus, J. bryoides, J. bufonius, J. bulbosus, J. caesariensis, J. canadensis, J. capillaris, J. capitatus, J. castaneus, J. chlorocephalus, J. compressus, J. confusus, J. cooperi, J. coriaceus, J. covillei, J. debilis, J. dichotomus, J. diffusissimus, J. drummondii, J. dubius, J. dudleyi, J. effusus, J. elliottii, J. ensifolius, J. falcatus, J. filiformis, J. filipendulus, J. georgianus, J. gerardii, J. greenei, J. gymnocarpus, J. hallii, J. hemiendytus, J. howellii, J. inflexus, J. interior, J. kelloggii, J. leiospermus, J. lesueurii, J. longistylis, J. luciensis, J. macrandrus, J. macrophyllus, J. marginatus, J. maritimus, J. megacephalus, J. mertensianus, J. militaris, J. nevadensis, J. nodatus, J. nodosus, J. occidentalis, J. orthophyllus, J. oxymeris, J. parryi, J. patens, J. pelocarpus, J. pervetus, J. phaeocephalus, J. polycephalus, J. regelii, J. repens, J. roemerianus, J. scirpoides, J. secundus, J. squarrosus, J. stygius, J. subcaudatus, J. subtilis, J. supiniformis, J. tenuis, J. texanus, J. textilis, J. tiehmii, J. torreyi, J. trifidus, J. triformis, J. triglumis, J. trigonocarpus, J. uncialis, J. validus, J. vaseyi, J. xiphioides	J. acuminatus, J. acutiflorus, J. acutus, J. alpinoarticulatus, J. anthelatus, J. arcticus, J. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, J. brachycephalus, J. brachyphyllus, J. brevicaudatus, J. bryoides, J. bufonius, J. bulbosus, J. caesariensis, J. canadensis, J. capillaris, J. capitatus, J. castaneus, J. chlorocephalus, J. compressus, J. confusus, J. cooperi, J. coriaceus, J. covillei, J. debilis, J. dichotomus, J. diffusissimus, J. drummondii, J. dubius, J. dudleyi, J. effusus, J. elliottii, J. ensifolius, J. falcatus, J. filiformis, J. filipendulus, J. georgianus, J. gerardii, J. greenei, J. gymnocarpus, J. hallii, J. hemiendytus, J. howellii, J. inflexus, J. kelloggii, J. leiospermus, J. lesueurii, J. longistylis, J. luciensis, J. macrandrus, J. macrophyllus, J. marginatus, J. maritimus, J. megacephalus, J. mertensianus, J. militaris, J. nevadensis, J. nodatus, J. nodosus, J. occidentalis, J. orthophyllus, J. oxymeris, J. parryi, J. patens, J. pelocarpus, J. pervetus, J. phaeocephalus, J. polycephalus, J. regelii, J. repens, J. roemerianus, J. scirpoides, J. secundus, J. squarrosus, J. stygius, J. subcaudatus, J. subtilis, J. supiniformis, J. tenuis, J. texanus, J. textilis, J. tiehmii, J. torreyi, J. trifidus, J. triformis, J. triglumis, J. trigonocarpus, J. uncialis, J. validus, J. vaseyi, J. xiphioides
Subordinate taxa	J. acutus subsp. leopoldii
Synonyms		J. arizonicus, J. interior var. arizonicus, J. interior var. neomexicanus, J. monostichus, J. neomexicanus
Name authority	Linnaeus: Sp. Pl. 1: 325. (1753)	Wiegand: Bulletin of the Torrey Botanical Club 27: 516. (1900)
Web links	Local Web sites: CalFlora, CalPhotos 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, IL Wildflowers, KS Wildflowers, LA Plants, MN Wildflowers, MO Plants, 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 acutus

Juncus interior

sharp rush, spiny rush

inland rush, interior juncus, interior rush

Habit

Herbs, perennial, tufted, 2–6 dm.

Rhizomes

densely branching.

Culms

1–10.

Cataphylls

1–3.

Leaves

basal, 1–2(–3);

auricles whitish or purplish tinged, 0.2–0.4(–0.6) mm, scarious;

blade flat, 5–15 cm × 0.5–1.1 mm, margins entire.

Inflorescences

usually somewhat compact, 1.5–7 cm;

primary bract usually shorter than inflorescence.

Flowers

bracteoles 2;

tepals greenish, lanceolate, 3.3–4.4 mm, apex acuminate;

stamens 6, filaments 0.5–0.9 mm, anthers 0.4–0.6 mm;

style 0.1–0.2 mm.

Capsules

light tan or darker, 1-locular to pseudo-3-locular, ellipsoid to nearly globose, (3.3–)3.8–4.7 mm, nearly equal to or longer than tepals.

Seeds

tan, ellipsoid to lunate, 0.436–0.73 mm, not tailed.

= 80.

Juncus acutus

Juncus interior

Phenology

Flowering and fruiting late spring–early summer.

Habitat

Dry, often upland sites in prairies, exposed disturbed sites, and ditches in sandy or clayey soils

Distribution

AZ; CA; NV; South America; Mexico (Baja Calif); South Africa; Atlantic Islands

[WildflowerSearch map]

[BONAP county map]

AR; AZ; CO; IA; IL; IN; KS; KY; LA; MN; MO; MT; ND; NE; NM; OH; OK; SD; TN; UT; WI; WY; AB; MB; ON; QC; SK; Texas

[WildflowerSearch map]

[BONAP county map]

Discussion

Subspecies 2 (1 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source

FNA vol. 22, p. 237.

FNA vol. 22.

Parent taxa

Juncaceae > Juncus > subg. Juncus

Juncaceae > Juncus > subg. Poiophylli

Sibling taxa

J. acuminatus, J. acutiflorus, J. alpinoarticulatus, J. anthelatus, J. arcticus, J. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, J. brachycephalus, J. brachyphyllus, J. brevicaudatus, J. bryoides, J. bufonius, J. bulbosus, J. caesariensis, J. canadensis, J. capillaris, J. capitatus, J. castaneus, J. chlorocephalus, J. compressus, J. confusus, J. cooperi, J. coriaceus, J. covillei, J. debilis, J. dichotomus, J. diffusissimus, J. drummondii, J. dubius, J. dudleyi, J. effusus, J. elliottii, J. ensifolius, J. falcatus, J. filiformis, J. filipendulus, J. georgianus, J. gerardii, J. greenei, J. gymnocarpus, J. hallii, J. hemiendytus, J. howellii, J. inflexus, J. interior, J. kelloggii, J. leiospermus, J. lesueurii, J. longistylis, J. luciensis, J. macrandrus, J. macrophyllus, J. marginatus, J. maritimus, J. megacephalus, J. mertensianus, J. militaris, J. nevadensis, J. nodatus, J. nodosus, J. occidentalis, J. orthophyllus, J. oxymeris, J. parryi, J. patens, J. pelocarpus, J. pervetus, J. phaeocephalus, J. polycephalus, J. regelii, J. repens, J. roemerianus, J. scirpoides, J. secundus, J. squarrosus, J. stygius, J. subcaudatus, J. subtilis, J. supiniformis, J. tenuis, J. texanus, J. textilis, J. tiehmii, J. torreyi, J. trifidus, J. triformis, J. triglumis, J. trigonocarpus, J. uncialis, J. validus, J. vaseyi, J. xiphioides

J. acuminatus, J. acutiflorus, J. acutus, J. alpinoarticulatus, J. anthelatus, J. arcticus, J. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, J. brachycephalus, J. brachyphyllus, J. brevicaudatus, J. bryoides, J. bufonius, J. bulbosus, J. caesariensis, J. canadensis, J. capillaris, J. capitatus, J. castaneus, J. chlorocephalus, J. compressus, J. confusus, J. cooperi, J. coriaceus, J. covillei, J. debilis, J. dichotomus, J. diffusissimus, J. drummondii, J. dubius, J. dudleyi, J. effusus, J. elliottii, J. ensifolius, J. falcatus, J. filiformis, J. filipendulus, J. georgianus, J. gerardii, J. greenei, J. gymnocarpus, J. hallii, J. hemiendytus, J. howellii, J. inflexus, J. kelloggii, J. leiospermus, J. lesueurii, J. longistylis, J. luciensis, J. macrandrus, J. macrophyllus, J. marginatus, J. maritimus, J. megacephalus, J. mertensianus, J. militaris, J. nevadensis, J. nodatus, J. nodosus, J. occidentalis, J. orthophyllus, J. oxymeris, J. parryi, J. patens, J. pelocarpus, J. pervetus, J. phaeocephalus, J. polycephalus, J. regelii, J. repens, J. roemerianus, J. scirpoides, J. secundus, J. squarrosus, J. stygius, J. subcaudatus, J. subtilis, J. supiniformis, J. tenuis, J. texanus, J. textilis, J. tiehmii, J. torreyi, J. trifidus, J. triformis, J. triglumis, J. trigonocarpus, J. uncialis, J. validus, J. vaseyi, J. xiphioides

Subordinate taxa

J. acutus subsp. leopoldii

Synonyms

J. arizonicus, J. interior var. arizonicus, J. interior var. neomexicanus, J. monostichus, J. neomexicanus

Name authority

Linnaeus: Sp. Pl. 1: 325. (1753)

Wiegand: Bulletin of the Torrey Botanical Club 27: 516. (1900)

Web links

Local floras: BC, CA, OR, WA
Local Web sites: CalFlora, CalPhotos, Flora NW, IL Wildflowers, KS Wildflowers, LA Plants, MN Wildflowers, MO Plants, PNW Herbaria
WildflowerSearch
iNaturalist (observations)
USDA Plants Database
LBJ Wildflower Center
SEINet
Plants of the World Online
Encyclopedia of Life
Wikipedia
Google Image Search

Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).

Choose a data source: Flora of North America, OregonFlora, UW Burke Herbarium

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Flora of North America species comparison

Juncus acutus

Juncus interior

Juncus acutus

Juncus interior