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Montana Field Guide

Montana Field Guides

Hooker's Physcomitrium Moss - Physcomitrium hookeri

Species of Concern
Native Species

Global Rank: G2G4
State Rank: S1

Agency Status
MNPS Threat Rank:

External Links

General Description
Plants: Growing in open or closely-packed tufts (Flowers 1973), small, pale green or occasionally brown. Stems 1-3 mm (FNA 2007), solitary or sometimes forked once or twice (Flowers 1973).

Leaves: Ovate or oblong-ovate, plane or concave, occasionally hood-shaped, upper leaves 2-2.5(-3) mm, much shriveled when dry (FNA 2007), spreading expansively when moist; apex acute or tapering to a point (Flowers 1973); margins not noticeably bordered (Lawton 1971), smooth, although swollen cells in the upper portion may cause unevenness; costa single, ending at the apex or just below (FNA 2007).

Leaf Cells: Distal laminal cells 4- to 6-sided (FNA 2007), with fine walls; lower laminal cells elongated (Lawton 1971).

Capsules ripen in spring (FNA 2007).

Diagnostic Characteristics
P. hookeri has smooth margins (sometimes uneven distally but not truly toothed), unlike the other members of Physcomitrium, which possess toothed leaves (FNA 2007).

Range Comments
Uncommon. Endemic to North America (Crum and Anderson 1981). Found in the west from AB s to UT; including KS, NE, IA, MN and ON in the central region; and known from ON, OH and NY in the east (FNA 2007). In Montana: Carter, Cascade, Fallon, and Ravalli Counties (Elliott 2016).

Observations in Montana Natural Heritage Program Database
Number of Observations: 3

(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 (FNA 2007).

Reproductive Characteristics
Autoicous or sometimes polygamous. Seta (1-)2-4(-6) mm tall. Capsule 0.8-1.5 mm, protruding slightly from or well beyond the tips of the perichaetial leaves, egg-shaped when young, eventually becoming pear- or bell-shaped; neck short, mostly well-defined, usually furrowed when dry (FNA 2007); operculum with an apiculous (Lawton 1971).

  • 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.
    • Flowers, S. 1973. Mosses: Utah and the West. Brigham Young University, Provo, Utah. 567 p.
    • 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.
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Citation for data on this website:
Hooker's Physcomitrium Moss — Physcomitrium hookeri.  Montana Field Guide.  .  Retrieved on , from