FNA: Juncus tenuis vs. Juncus polycephalus

	Juncus tenuis	Juncus polycephalus
	path rush, poverty or slender rush, poverty rush, slender rush	flatleaf rush, manyhead rush
Habit	Herbs, perennial, tufted, 1.5–5 dm.	Herbs, perennial, cespitose, 6–10 dm.
Rhizomes	densely branching.
Culms	few–20.	erect, 3–14 mm diam.
Cataphylls		absent.
Leaves	basal, (1–)2–3; auricles 2–5 mm, apex acute, membranous; blade flat, 3–12 cm × 0.5–1 mm, margins entire.	basal 2–3(–6), cauline 1–4, brownish green; auricles absent; blade 8–70 cm × 4–8 mm.
Inflorescences	5–40-flowered, borne congested or branch internodes ca. as long as tepals, ssomewhat loose, 1–5 cm; primary bract usually longer than inflorescence.	panicles of 16–82 heads, 10–30 cm; primary bract erect; heads 20–30-flowered, spheric, 8–12 mm diam.
Flowers	bracteoles 2; tepals greenish, lanceolate, 3.3–4.4 mm; outer and inner series nearly equal; stamens 6, filaments 0.5–0.9 mm, anthers 0.1–0.2 mm; style 0.1–0.2 mm.	tepals green to reddish, lance-subulate, 3–4 mm, nearly equal, apex acuminate; stamens 3, anthers 1/3–1/2 length of filaments.
Capsules	tan or light brown, 1-locular to pseudo-3-locular, ellipsoid, (3.3–)3.8–4.7 × (1.1–)1.3–1.7 mm, nearly equal to tepals.	exserted, straw-colored, 1-locular, narrowly ovoid, 4–5 mm, apex tapering to beak, remaining after dehiscence.
Seeds	tan, ellipsoid to lunate, (0.52–)5.5–0.65(–0.7) mm, not tailed.	lance-ellipsoid, 0.5–0.6 mm, not tailed.
2n	= 80.

	Juncus tenuis	Juncus polycephalus
Phenology	Flowering spring–early summer.	Fruiting spring–fall.
Habitat	Exposed or shaded sites in soils ranging from sandy to clayey under moist or drier conditions, oftentimes these sites naturally or otherwise disturbed (e.g., game or human trails)	Wet or seasonally wet shores, depressions, occasionally in fairly deep water of streams, usually with a peaty or mucky substrate, occasionally sandy to gravelly
Elevation		0–100 m (0–300 ft)
Distribution	AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NS; ON; PE; QC; SK [Introduced worldwide] [WildflowerSearch map] [BONAP county map]	AL; FL; GA; LA; MD; MS; NC; SC; TX [WildflowerSearch map]
Discussion	Juncus tenuis occurs throughout North America. It is particularly abundant in northeastern United States and eastern Canada, although infrequent in the south and west. Through the use of isozyme electrophoresis, hybridization can be demonstrated between various members of the Juncus tenuis complex, including Juncus tenuis, J. anthelatus, J. interior, J. secundus, and J. dichotomus (R. E. Brooks, unpubl.). Juncus ××oronensis is thought to be a hybrid between J. tenuis and J. vaseyi in the northeast. (Discussion copyrighted by Flora of North America; reprinted with permission.)
Source	FNA vol. 22.	FNA vol. 22.
Parent taxa	Juncaceae > Juncus > subg. Poiophylli	Juncaceae > Juncus > subg. Ensifolii
Sibling taxa	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. 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. 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. 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. 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
Synonyms	J. bicornis, J. bicornis var. williamsii, J. macer, J. macer, J. macer var. williamsii, J. tenuis var. bicornis, J. tenuis var. multicornis, J. tenuis var. williamsii	J. echinatus, J. engelmannii
Name authority	Willdenow: Sp. Pl. 2(1): 214. (1799)	Michaux: Flora Boreali-Americana 1: 192. 1803 (as polycephalos)
Web links	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, Go Botany, IL Wildflowers, KS Wildflowers, LA Plants, MD Biodiversity, MI Flora, 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	Local Web sites: LA Plants, MD Biodiversity WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Juncus polycephalus

path rush, poverty or slender rush, poverty rush, slender rush

flatleaf rush, manyhead rush

Habit

Herbs, perennial, tufted, 1.5–5 dm.

Herbs, perennial, cespitose, 6–10 dm.

Rhizomes

densely branching.

Culms

few–20.

erect, 3–14 mm diam.

Cataphylls

absent.

Leaves

basal, (1–)2–3;

auricles 2–5 mm, apex acute, membranous;

blade flat, 3–12 cm × 0.5–1 mm, margins entire.

basal 2–3(–6), cauline 1–4, brownish green;

auricles absent;

blade 8–70 cm × 4–8 mm.

Inflorescences

5–40-flowered, borne congested or branch internodes ca. as long as tepals, ssomewhat loose, 1–5 cm;

primary bract usually longer than inflorescence.

panicles of 16–82 heads, 10–30 cm;

primary bract erect;

heads 20–30-flowered, spheric, 8–12 mm diam.

Flowers

bracteoles 2;

tepals greenish, lanceolate, 3.3–4.4 mm;

outer and inner series nearly equal;

stamens 6, filaments 0.5–0.9 mm, anthers 0.1–0.2 mm;

style 0.1–0.2 mm.

tepals green to reddish, lance-subulate, 3–4 mm, nearly equal, apex acuminate;

stamens 3, anthers 1/3–1/2 length of filaments.

Capsules

tan or light brown, 1-locular to pseudo-3-locular, ellipsoid, (3.3–)3.8–4.7 × (1.1–)1.3–1.7 mm, nearly equal to tepals.

exserted, straw-colored, 1-locular, narrowly ovoid, 4–5 mm, apex tapering to beak, remaining after dehiscence.

Seeds

tan, ellipsoid to lunate, (0.52–)5.5–0.65(–0.7) mm, not tailed.

lance-ellipsoid, 0.5–0.6 mm, not tailed.

= 80.

Juncus polycephalus

Phenology

Flowering spring–early summer.

Fruiting spring–fall.

Habitat

Exposed or shaded sites in soils ranging from sandy to clayey under moist or drier conditions, oftentimes these sites naturally or otherwise disturbed (e.g., game or human trails)

Wet or seasonally wet shores, depressions, occasionally in fairly deep water of streams, usually with a peaty or mucky substrate, occasionally sandy to gravelly

Elevation

0–100 m (0–300 ft)

Distribution

AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NS; ON; PE; QC; SK [Introduced worldwide]

[WildflowerSearch map]

[BONAP county map]

AL; FL; GA; LA; MD; MS; NC; SC; TX

[WildflowerSearch map]

Discussion

Juncus tenuis occurs throughout North America. It is particularly abundant in northeastern United States and eastern Canada, although infrequent in the south and west.

Through the use of isozyme electrophoresis, hybridization can be demonstrated between various members of the Juncus tenuis complex, including Juncus tenuis, J. anthelatus, J. interior, J. secundus, and J. dichotomus (R. E. Brooks, unpubl.). Juncus ××oronensis is thought to be a hybrid between J. tenuis and J. vaseyi in the northeast.

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

Source

FNA vol. 22.

Parent taxa

Juncaceae > Juncus > subg. Poiophylli

Juncaceae > Juncus > subg. Ensifolii

Sibling taxa

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. 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. 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. 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. 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

Synonyms

J. bicornis, J. bicornis var. williamsii, J. macer, J. macer, J. macer var. williamsii, J. tenuis var. bicornis, J. tenuis var. multicornis, J. tenuis var. williamsii

J. echinatus, J. engelmannii

Name authority

Willdenow: Sp. Pl. 2(1): 214. (1799)

Michaux: Flora Boreali-Americana 1: 192. 1803 (as polycephalos)

Web links

Local floras: BC, CA, OR, WA
Local Web sites: CalFlora, CalPhotos, Flora NW, Go Botany, IL Wildflowers, KS Wildflowers, LA Plants, MD Biodiversity, MI Flora, 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

Local Web sites: LA Plants, MD Biodiversity
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

The species comparison tool is brought to you by:

Flora of North America species comparison

Juncus tenuis

Juncus polycephalus

Juncus tenuis

Juncus polycephalus