Jepson eFlora: Taxon page
Vascular Plants of California
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Juncus marginatus

Higher Taxonomy
Family: JuncaceaeView DescriptionDichotomous Key
Common Name: RUSH FAMILY
Habit: Annual, perennial herb generally from rhizomes. Stem: round or flat. Leaf: generally basal; sheath margins fused, or overlapping and generally with 2 ear-like extensions at blade junction; blade round, flat, or vestigial, glabrous or margin hairy. Inflorescence: head-like clusters or flowers 1, variously arranged; bracts subtending inflorescence 2, generally leaf-like; bracts subtending inflorescence branches 1--2, reduced; bractlets subtending flowers generally 1--2, generally translucent. Flower: generally bisexual, radial; sepals and petals similar, persistent, scale-like, green to brown or +- purple-black; stamens generally 3 or 6, anthers linear, persistent; pistil 1, ovary superior, chambers generally 1 or 3, placentas 1 and basal or 3 and axile or parietal, stigmas generally > style. Fruit: capsule, loculicidal. Seed: 3--many, generally with white appendages on 1 or both ends.
Genera In Family: 7 genera, 440 species: temperate, arctic, and tropical mountains. Note: Flowers late spring to early fall.
eFlora Treatment Author: Peter F. Zika, except as noted
Scientific Editor: Douglas H. Goldman, Bruce G. Baldwin.
Genus: JuncusView DescriptionDichotomous Key

Common Name: RUSH
Habit: Rhizome 0 or generally with scale-like leaves. Stem: generally cylindric or flat. Leaf: blade well developed and cylindric or flat, occasionally closely resembling stem, or reduced to small point; crosswalls generally present; appendages generally present at blade-sheath junction. Inflorescence: generally terminal, appearing lateral when pushed aside by inflorescence bract; bractlets 0--2. Flower: sepals, petals similar; stamens generally 3 or 6(2); pistil 1, ovary chambers 1--3, placentas axile or parietal, stigmas generally 3(2). Seed: many.
Species In Genus: 315 species: worldwide, especially northern hemisphere. Etymology: (Latin: to join or bind, from use of stems) Note: All species with leaf crosswalls may have leaves, stems swollen, deformed by sucking insects. Fruiting time given instead of flowering time. Plants included in TJM2 as Juncus brachyphyllus now treated in California as a new species, Juncus trilocularis (Zika 2012 Rhodora 114:309--329); Juncus bulbosus, Juncus dichotomus, and Juncus elliottii, only noted as naturalized in TJM2, now fully treated.
eFlora Treatment Author: Peter F. Zika
Reference: [Ertter 1986 Mem New York Bot Gard 39:1--90]
Juncus marginatus Rostk.
Habit: Perennial herb 15--70 cm; rhizome short, thick, knobby. Stem: slender. Leaf: distributed along stem; sheath appendages rounded, scarious; blade with flat side toward stem, exceeded by inflorescence, 1--6 mm wide, not stiff, crosswalls 0. Inflorescence: open to compact; lowest bract << inflorescence; clusters 2--40, 5--12-flowered. Flower: perianth parts 2.5--3.5 mm, sepals < petals, sharply acute, petals blunter, +- red-brown; stamens 3, filaments >> +- purple-red anthers. Fruit: = perianth, spheric; beak 0. Seed: 0.5 mm, ovoid, brown; appendages minute. Chromosomes: 2n=38,40.
Ecology: Locally common in sunny seeps, shallow water, abandoned placer mines; Elevation: 300--950 m. Bioregional Distribution: CaRF (Tehama Co.), n SNF (Nevada Co.); Distribution Outside California: Oregon, native from Arizona to New Mexico, eastern North America, Central America, South America. Fruiting Time: Jul--Aug
Synonyms: Juncus marginatus var. marginatus
Unabridged Note: Juncus marginatus has been tracked as a rare native plant in California, but this is a species with its main distribution in eastern North America. 2 of the 3 known California populations are on greatly disturbed ground (former placer mines). The species was not detected in California until 1965, and it is a recent adventive in Oregon. I can see no strong evidence to consider it native, with the next closest population +- 900 km to the southeastern in Arizona. One of the populations is growing with another wetland species obviously introduced from eastern North America,Vaccinium macrocarpon. The culture of cranberry vines has commonly resulted in the unintentional establishment of many small-seeded wetland species native to the east (Zika 2003 J Torr Bot Soc 130:43--46).
Jepson eFlora Author: Peter F. Zika
Reference: [Ertter 1986 Mem New York Bot Gard 39:1--90]
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)

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Botanical illustration including Juncus marginatus

botanical illustration including Juncus marginatus


Citation for this treatment: Peter F. Zika 2015, Juncus marginatus, in Jepson Flora Project (eds.) Jepson eFlora, Revision 3,, accessed on August 12, 2022.

Citation for the whole project: Jepson Flora Project (eds.) 2022, Jepson eFlora,, accessed on August 12, 2022.

Juncus marginatus
click for enlargement
© 2003 Steve Matson
Juncus marginatus
click for enlargement
© 2003 Steve Matson
Juncus marginatus
click for enlargement
© 2003 Steve Matson
Juncus marginatus
click for enlargement
© 2003 Steve Matson

More photos of Juncus marginatus in CalPhotos

Geographic subdivisions for Juncus marginatus:
CaRF (Tehama Co.), n SNF (Nevada Co.)
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map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).


Data provided by the participants of the  Consortium of California Herbaria.
View all CCH records
All markers link to CCH specimen records. The original determination is shown in the popup window.
Blue markers indicate specimens that map to one of the expected Jepson geographic subdivisions (see left map). Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.

CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time (fruiting time in some monocot genera).