Plants and Animals

Juncus stygius Moor rush

species photo
Emmet J. Judziewicz

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

US Status: No Status/Not Listed
State Status: E - Endangered (legally protected)
Global Rank: G5 - Secure
State Rank: S1S2 - Rank is uncertain, ranging from critically imperiled to imperiled


CountyNumber of OccurrencesYear Last Observed
Alger 1 2019
Delta 1 1985
Keweenaw 1 2004
Luce 2 1989
Mackinac 2 2014
Marquette 2 2017

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).

Management Recommendations

This species requires protection of habitat and maintenance of hydrology.

Survey Methods

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

  • Meander search

    • Survey Period: From fourth week of June to fourth week of July


Survey References

  • Elzinga, C.L., D.W. Salzer, and J.W. Willoughby. 1998. Measuring and Monitoring Plant Populations. The Nature Conservancy and Bureau of Land Management, Denver. BLM Technical Reference 1730-1. 477pp.
  • Goff, G.F., G.A. Dawson, and J.J. Rochow. 1982. Site examination for Threatened and Endangered plant species. Environmental Management 6(4): 307-316
  • Nelson, J.R. 1984. Rare Plant Field Survey Guidelines. In: J.P. Smith and R. York. Inventory of rare and endangered vascular plants of California. 3rd Ed. California Native Plant Society, Berkeley. 174pp.
  • Nelson, J.R. 1986. Rare Plant Surveys: Techniques For Impact Assessment. Natural Areas Journal 5(3):18-30.
  • Nelson, J.R. 1987. Rare Plant Surveys: Techniques for Impact Assessment. In: Conservation and management of rare and endangered plants. Ed. T.S. Elias. California Native Plant Society, Sacramento. 8pp.

Technical References

  • Clemants, S.E. 1990. Juncaceae (Rush Family) of New York State. Bulletin Number 475. New York State Museum, Albany, NY. 67 pp.
  • Coffin, B. and L. Pfannmuller, eds. 1988. Minnesota's Endangered Flora and Fauna. University of Minnesota Press, Minneapolis. 473pp.
  • Flora of North America Editorial Committee. 2000. Flora of North America, North of Mexico. Volume 22: Magnoliaphyta: Alismatidae, Arecidae, Commelinidae (in part), and Zingiberidae. Oxford University Press, New York. 352pp.
  • Gleason, H. A., and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. Second edition. The New York Botanical Garden, Bronx. 910pp.
  • Gray, A. 1950. Gray's Manual of Botany; eighth ed. Van Nostrand Reinghold, New York. 1632pp.
  • Holmgren, N.H. 1998. Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the vascular plants of Northeastern United States and adjacent Canada. New York Botanical Garden, Bronx. 937pp.
  • Scoggan, H.J. 1978. The Flora of Canada. National Museum of Natural Science Publications Botany 4: 1711pp.
  • Voss, E. G. 1972. Michigan Flora. Part I. Gymnosperms and Monocots. Bulletin of the Cranbrook Institute of Science and University of Michigan Herbarium. 488pp.