Juncus stygius
Moor rush
Image of Juncus stygius

Photo by Bradford S. Slaughter 

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Key Characteristics

Perennial loosely clustered rush of bogs and fens in the Upper Peninsula; leaves without hard cross-partitions; inflorescence terminal, hemispherical, with only 1-4 flowers; margins of tepals white; seeds relatively large (3 mm) with pale tails.

Status and Rank

  • State Status: T
  • State Rank: S1S2
  • Global Rank: G5


County NameNumber of OccurrencesYear Last Observed
Distribution map for Juncus stygius

Updated 5/15/2018. Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


Found in open to semi-open white cedar-black spruce-tamarack fens. It also occurs on sedge-sphagnum floating mats formed over alkaline lakes and peatland complexes with patterned fen, consisting of low, parallel peat ridges (strings) alternating with shallow, narrow, wet depressions (flarks).

Natural Community Types


For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Associated Plants

Trees: Larix laricina (tamarack), Picea mariana (black spruce), Thuja occidentalis (northern white-cedar)

Shrubs: Andromeda glaucophylla (bog rosemary), Chamaedaphne calyculata (leatherleaf), Myrica gale (sweet gale)

Herbs and Dwarf Shrubs: Calopogon tuberosus (grass-pink), Carex gynocrates, C. lasiocarpa, C. limosa, C. livida, Cladium mariscoides (twig-rush), Drosera intermedia (spatulate-leaved sundew), D. rotundifolia (round-leaved sundew), Lycopodiella inundata (bog clubmoss), Menyanthes trifoliata (buckbean), Pogonia ophioglossoides (rose pogonia), Rhynchospora alba (beak-rush), R. fusca (beak-rush), Sarracenia purpurea (pitcher-plant), Trichophorum alpinum (bulrush), Utricularia cornuta (horned bladderwort), Vaccinium oxycoccos (small cranberry).


This species requires protection of habitat and maintenance of hydrology.

General Survey Guidelines

Random meander search covers areas that appear likely to have rare taxa, based on habitat and the judgement of the investigator.

Survey Methods

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at http://mnfi.anr.msu.edu/explorer [Accessed Sep 25, 2018]


Survey References

Technical References

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