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Montana Field Guides

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).

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.
    • Elliot, J.C., and A.K. Pipp. 2018. A Checklist of Montana Mosses (1880-2018). December 5. 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