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A Haircap Moss - Polytrichastrum longisetum
Other Names:  Polytrichum longisetum

Native Species

Global Rank: G5
State Rank: SNR

Agency Status
MNPS Threat Rank:

External Links

General Description
Plants: Acrocarpous, growing in uncrowded clumps of erect shoots, deep green. Stems 2-10 cm in height, borne from short, subterranean rhizomes (FNA 2007).

Leaves: Somewhat twisted, curved and bent when dry, spreading close to 90 degrees with the leaf apex turned back and down when damp, 5-10 mm in length, the short sheathing base somewhat yellow with transparent, smooth margins, narrowing to the divergent blade with little joint tissue present where the two meet; blade slender and lance-shaped; margins with sharp teeth, sometimes fine, along the blade almost to the sheath; costa shortly extending beyond the apex (FNA 2007).

Leaf Cells: Marginal lamina 5-12 cells in width, bent up and inward somewhat (“holding in” the lamellae), the marginal teeth of the blade each consisting of 1 long cell (FNA 2007); lamellae 18-50, green, nearly completely obscuring the ventral leaf surface from shoulder to leaf tip (Crum & Anderson et al., 1981), from a side-view appearing like a wall of cells that are smooth to finely toothed along the top and 3-7 cells in height, the topmost (marginal) lamellar cell in X-section somewhat egg-shaped to oblong, more often taller than broad; sheath cells quadrangular, short; costa in X-section with large guide cells and a dorsal stereid band (FNA 2007).

Range Comments
North American Range

Canada: NT, BC to NL and NS; USA: AK, MT to CO, also MN, WI, IL, NY and PA (FNA 2007). Known in Montana from Carbon, Flathead, Lincoln, and Sanders Counties (Elliott & Pipp, 2016).

Observations in Montana Natural Heritage Program Database
Number of Observations: 4

(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)

Damp humus and soil in evergreen forest (Crum & Anderson et al., 1981), peaty bogs (from acidic to basic), tundra (FNA 2007); in alpine and subalpine habitats (Elliott & Pipp, 2016).

Reproductive Characteristics
Dioicous. Perichaetial bracts a little larger and with a dentate awn but otherwise resembling stem leaves. Seta single, 4-6 cm in height, yellow above, russet below. Capsule ochre, 3-5 mm in length, typically with 5 or 6 angles (FNA 2007), the theca 3-4.5 mm in length (Lawton 1971), wider than the neck; peristome with about 50 teeth of varying profiles and sizes. Calyptra sheltering the upper part of the capsule, draping like a hood and covered with matted hairs (polytrichoid) (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.
    • Lawton, E. 1971. Moss Flora of the Pacific Northwest. Hattori Botanical Laboratory. Japan: Yamabuki-cho, Shinjuku-ku, Tokyo. 362 pages plus appendices.
  • Additional ReferencesLegend:   View Online Publication
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    • Lawton, E. 1971. Keys for the Identification of the Mosses on the Pacific Northwest. Reprinted from 'Moss Flora of the Pacific Northwest'. Published as Supplement No. 2 of the Journal of the Hattori Botanical Laboratory. Nichinan, Miyazaki, Japan. 66 pp.
    • Malcolm, B., N. Malcolm, J. Shevock, and D. Norris. 2009. California Mosses. Nelson, New Zealand: Micro-Optics Press. 430 pp.
    • Smith, A.J.E. 1980. The Moss Flora of Britain and Ireland. Cambridge University Press, Cambridge. 705 pp.
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Citation for data on this website:
A Haircap Moss — Polytrichastrum longisetum.  Montana Field Guide.  .  Retrieved on , from