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Montana Field Guide

Montana Field Guides

Fen Peatmoss - Sphagnum warnstorfii

Native Species

Global Rank: G5
State Rank: SNR

Agency Status


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General Description
Plants: More green when shaded, redder or deep purple when exposed (Crum and Anderson et al. 1981), slim, frequently displaying a tinge of blue when dry, the capitula level on top and radiate (FNA 2007).

Stems and Stem Leaves: Stems green, red, or in-between. Stem leaves comparable in size to the branch leaves, tongue-shaped and somewhat trigonal, 1.1-1.4 mm in length; apex wide and rounded or a slender cut-off point; border quite wide proximally (FNA 2007).

Branches and Branch Stem Leaves: Branch stems green, typically 5-ranked, narrowing and long, the branch clusters with 3-4 branches, 2 of them spreading, the others pendent. Branch leaves lance- and somewhat egg-shaped, 0.9-1.4 mm in length, cupped, straight; apex strongly rolled upward and inward (FNA 2007).

Stem and Stem Leaf Cells: Outermost cortical cells of the stem in 2-4 tiers, finely-walled, lacking fibrils and pores. Stem leaf cells diamond-shaped, lacking fibrils, typically partitioned once, but sometimes not at all (FNA 2007).

Branch and Branch Leaf Cells: Branch stems encompassed by 1 tier of swollen, fine-walled hyaline cells which lack fibrils, along with some individual and/or some small clusters of retort cells, each exhibiting 1 pore. Hyaline cells of the branch leaves lacking fibrils, with ringed pores on the convex (outer) leaf surface along the cell margins that are juxtaposed to green cells, tiny at the leaf apex, suddenly becoming big and elliptical proximally, the concave (inner) leaf surface displaying big round pores in the lower leaf edges and at the base; green cells in X-section trigonal to unevenly 4-sided, more of their area visible on the inner than on the outer leaf surface, the end walls at each surface relatively thin (FNA 2007).

Fruit ripening in the latter part of the summer through the first part of fall (FNA 2007).

Range Comments
North American Range

Canada: Known in all provinces and territories except PE; USA: in most northeastern states, extending w to IN, WI, MN, and SD, also NC, and in the western states of WA, ID, MT, WY, UT and CO (FNA 2007). Known in Montana from Beaverhead, Carbon, Cascade, Deer Lodge, Flathead, Gallatin, Glacier, Lake, Lincoln, Missoula, Park, Ravalli, and Stillwater Counties (Elliott 2016).

Observations in Montana Natural Heritage Program Database
Number of Observations: 107

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Wet soil and peat (Elliott 2016) in medium fens and richer, minerotrophic, (FNA 2007), a prominent calciphile (Crum and Anderson et al 1981).

Reproductive Characteristics
Dioicous. Fruiting infrequently (FNA 2007).

  • Literature Cited AboveLegend:   View Online Publication
    • Crum, H.A. and L.E. Anderson. 1981. Mosses of Eastern North America. 2 volumes. Columbia University Press, New York. 1328 pp.
    • Elliott, J.C. and A.K. Pipp. 2018. A Checklist of Montana Mosses (1880-2018). Updated 3 January, 2020. Montana Natural Heritage Program, Helena, Montana. 73 pp.
    • Flora of North America Editorial Committee, eds. 2007. Flora of North America North of Mexico. Volume 27. Bryophytes: Mosses, Part 1. Oxford University Press, Inc., NY. xxi + 713 pp.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Elliot, J. C. 1993. Second checklist of Montana mosses. Unpublished report. U.S. Forest Service, Region 1. Missoula, MT. 45 pp.
    • Flowers, S. 1973. Mosses: Utah and the West. Brigham Young University, Provo, Utah. 567 p.
    • Smith, A.J.E. 1980. The Moss Flora of Britain and Ireland. Cambridge University Press, Cambridge. 705 pp.
  • Web Search Engines for Articles on "Fen Peatmoss"
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Citation for data on this website:
Fen Peatmoss — Sphagnum warnstorfii.  Montana Field Guide.  .  Retrieved on , from