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A Dry Rock Moss - Grimmia mollis
Other Names:  A Black Rock Moss, Hydrogrimmia mollis

Potential Species of Concern
Native Species

Global Rank: G5
State Rank: SH

Agency Status
MNPS Threat Rank:

External Links

General Description
Plant: Loose patches. Green. Stems 1.0-5.0 cm tall. Stem X-S with a central strand.

Leaf: Oblong to ovate-lanceolate, 2.0-3.0 x 0.8-1.0 mm, and not keeled. Awn appearing absent. Apex muticous and rounded to cucullate. Both margins plane, but incurved distally. Costa ends well before apex (subpercurrent) and does not project on abaxial side (not keeled).

Leaf Cells: Basal laminal cells near costa and near margin; and median laminal cells are quadrate and thin-walled. X-S: distal laminal cells are 1-layered.

Diagnostic Characteristics
Its distinctive characteristics include the habitat, uniform cells, and subpercurrent costa.

Species Range

Range Comments
Greenland; Canada: AB, BC, QC, YT; USA: AK, CA, CO, MT, WA; Eurasia (FNA 2007). In Montana: Flathead and Glacier Counties (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)

Wet, acidic rocks in alpine to boreal habitats. Moderate to high elevations (3,280 – 13,450 feet). This is an arctic-alpine species and often grows near glacial streams. Species is widespread, but never commonly found.

Reproductive Characteristics
Dioicous. Seta is 2.0-3.0 mm tall, straight, and yellowish. Capsules are sporadically found, exserted, yellowish, smooth, and oblong-ovoid to cylindric.

  • Literature Cited AboveLegend:   View Online Publication
    • 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.
  • 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.
    • Lawton, E. 1971. Moss Flora of the Pacific Northwest. Hattori Botanical Laboratory. Japan: Yamabuki-cho, Shinjuku-ku, Tokyo. 362 pages plus appendices.
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Citation for data on this website:
A Dry Rock Moss — Grimmia mollis.  Montana Field Guide.  .  Retrieved on , from