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- For information on Wisconsin's rare plants, contact:
- Kevin Doyle
608-416-3377
Bog Rush (Juncus stygius)

Photo by Ryan O'Connor, WDNR
Life history
Species overview
Bog Rush (Juncus stygius), a Wisconsin Endangered plant, is found in cold fens. Blooming occurs late June through early July; fruiting occurs throughout July. The optimal identification period for this species is early July.
Synonyms: Juncus stygius ssp. americanus, Juncus stygius var. americanus
Identification
- Distinguishing characteristics: Seeds 2 to 3 mm with pale tails or appendages at both ends; 6 stamens; leaves very slender.
- Flower characteristics: Inflorescence of 1 to 3 compact heads, each 1- to 4-flowered, 1 cm; petals wide and obtuse; stamens 6; anthers much shorter than the filaments.
- Fruit characteristics: Ellipsoid, 6 to 8.5 mm, conspicuously tipped with a short, sharp, abrupt point; seeds 2 to 3 mm, with a thick pale appendage (or tail) at each end about as long as the body.
- Leaf characteristics: Basal leaves 1 to 3, or one cauline leaf above the middle; blades very narrow, sheaths firm, usually with slightly prolonged ear-shaped appendages.
Phenology
- Blooming phenology: late June through early July
- Fruiting phenology: throughout July
- Optimum time to identify: The optimal identification period for this species is early July
Other
- Growth form: Graminoid
- Vegetative reproduction: Rhizomatous
- Life cycle: Perennial
- Comments: Associated Species: Carex livida, Scirpus hudsonianus, Xyris montana, Arethusa bulbosa, Rhynchospora fusca, Utricularia cornuta, Triglochin maritimum, Calopogon tuberosus.
State status
Status and Natural Heritage Inventory documented occurrences in
Wisconsin
The table below provides information about the protected status -
state and federal - and the rank (S and G Ranks) for Bog Rush
(Juncus stygius). See the Working
List Key for more information about abbreviations. Counties shaded
blue have documented occurrences for this species in the Wisconsin
Natural Heritage Inventory database.
The map is provided as a general reference of where this species has
been found to date and is not meant as a range map.
Summary Information |
State Status | END |
Federal Status in Wisconsin | none |
State Rank | S1 |
Global Rank | G5 |
Tracked by NHI | Y |
Habitats and landscapes
The Natural Heritage Inventory has developed scores indicating the degree to which each of Wisconsin's rare plant species is associated with a particular natural community or ecological landscape. This information is similar to that found in the Wildlife Action Plan for animals. As this is a work in progress, we welcome your suggestions and feedback.
General habitat information
- Habitat description: Found in cold fens.
- Soils: Wet soils.
Natural communities
This table lists the natural communities that are associated with Bog Rush. Scores for natural community associations are: "significant" association (score=3), "moderate association" (score=2) or the species can be present but is only weakly associated with the community (score=1).
Ecological landscapes
This table lists the ecological landscape association scores for Bog Rush. The scores (3=High, 2=Moderate, 1=Low, 0=None) also correspond to the map.
Species guidance
The Endangered Resources Program has developed avoidance measures and management guidelines for plants on the Natural Heritage Working List. These are a work in progress, and we welcome your suggestions and feedback. Sources used in developing this information can be found here.
Avoidance measures
These are specific actions designed to avoid "take" (mortality) of this species.
- Avoid known individual plant locations and conduct operations elsewhere when they are least likely to cause damage. Ideally, this would involve frozen, snow-covered ground. However, in areas of the state where frozen conditions are unreliable, very dry soils late in the growing season might be the best available alternative. Consult with a biologist, if needed.
- Avoid broadcast spraying of herbicides; use care with spot spraying.
Management guidance
Management guidelines are additional considerations that may help maintain or enhance habitat for this species
- This species is likely sensitive to water quality. Following BMPs around streams and buffering associated drainages will reduce eutrophication and prevent water quality degradation.
- Survey for and control invasive plants prior to conducting timber operations, as these can be spread by vehicles and often respond vigorously to increased light; see forestry BMPs for invasive species.
- Minimize disturbance to hydrology, including soil disturbance from rutting.
- Avoid rapid and dramatic reductions in canopy cover or basal area in wet areas to reduce risk of swamping.
Other resources
Links to additional Bog Rush information
Other links related to vascular plants (all exit the DNR website)
Photos
Click to view a larger version. Please considering donating a photo to the Natural Heritage Conservation Program for educational uses. Photo use

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Photo © Wisconsin DNR.

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Photo by Kevin Doyle, Wisconsin DNR.

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Photo by Kevin Doyle, Wisconsin DNR.

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Photo by Ryan O'Connor, Wisconsin DNR.

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Photo by Ryan O'Connor, Wisconsin DNR.
Support for Wisconsin's rare plant information has been provided by the Division of Forestry, the Endangered Resources Fund and the Wisconsin Rare Plant Preservation Fund. To donate, visit the Natural Resources Foundation of Wisconsin [exit DNR].
Last revised: Wednesday, May 05, 2021