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Montana Field Guide

Montana Field Guides

Silky Urn Moss - Fabronia pusilla
Other Names:  Fabronia Moss

Species of Concern
Native Species

Global Rank: G4G5
State Rank: S1

Agency Status
MNPS Threat Rank:

External Links

General Description
Plants: Very small with stems level to the ground (FNA 2014).

Leaves: Somewhat flattened against the stem when dry, spreading when wet, 0.4-0.8 mm long (FNA 2014), 0.18-0.35 mm wide, ovate-lanceolate (Lawton 1971); edges ciliate-dentate with the teeth frequently terminating in linear cells; (FNA 2014); apex long-acuminate or subulate with tip consisting of a single long cell; costa single, frequently short, up to 1/2 leaf length, rarely lacking (Lawton 1971).

Leaf Cells: Laminal cells rhomboidal; alar region consisting of several lines of quadrate cells; the rhombic basal laminal cells sometimes rounded (FNA 2014) or quadrate from the midrib to the margins, often reaching farther up at the margins than along the costa, the cells progressively elongating distally (Lawton 1971), smooth; cells at the apex linear (FNA 2014).

Capsules ripen late-spring to summer (FNA 2014).

Diagnostic Characteristics
Its ciliate-toothed and long-acuminate leaves make Fabronia pusilla easily identifiable (FNA 2014).

Species Range

Range Comments
Canada: BC; USA: AZ, CA, CO, ID, OR, WA; Mexico (Baja California Sur); Europe; n Africa (FNA 2014). In Montana: Madison County (Elliott 2016).

Observations in Montana Natural Heritage Program Database
Number of Observations: 1

(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)

Rock and bark at bottom of trees. Low to high elevations (FNA 2014).

Reproductive Characteristics
Autoicous. Seta solitary, pale yellow, upright, smooth (FNA 2014), 2-3 mm. Capsule brown; theca 0.5-0.8 mm in length; peristome teeth papillose (Lawton 1971).

  • Literature Cited AboveLegend:   View Online Publication
    • 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. 2014. Flora of North America North of Mexico. Volume 28. Bryophytes: Mosses, Part 2. Oxford University Press, Inc., NY. xxi + 702 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
    Do you know of a citation we're missing?
    • 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:
Silky Urn Moss — Fabronia pusilla.  Montana Field Guide.  .  Retrieved on , from