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Rambling Round-headed Mountain Moss - Rhytidiadelphus loreus
Other Names:  A Shaggy Moss

Native Species

Global Rank: G5
State Rank: SNR

Agency Status
MNPS Threat Rank:

External Links

General Description
Plants: Pleurocarpous (Vitt 1988), growing in open mats (Crum and Anderson et al. 1981), to 15 cm in length, soft (FNA 2014) and stiff, green with yellow tones (Lawton 1971) or vivid green, somewhat glossy (Crum and Anderson et al. 1981). Primary stem growth seldom limited (not often dividing) with perichaetia and perigonia lateral; branches distant and erratically spaced to nearly pinnate, sometimes reaching 40 mm in length (FNA 2014), frequently curving at the apices, occasionally stoloniform (Lawton 1971); paraphyllia lacking; pseudoparaphyllia leaf-like (FNA 2014).

Stem Leaves: Overlapping below (Lawton 1971), but not otherwise densely spaced, spreading to about 45 degrees, frequently curved and pointing in one direction or curved back and downward above, 3.2-4.2 mm in length, sometimes reaching 1.4 mm in width, pleated below, not strongly wavy across the leaf, egg- to lance-shaped from a base that lightly envelops the stem, suddenly narrowed above to form a long, thin, and grooved acumen (FNA 2014); leaf edges finely-toothed (Crum and Anderson et al. 1981); costa extending to about 25% of the leaf length or less (FNA 2014), double, sometimes lacking (Lawton 1971).

Branch Leaves: Slenderly lance-shaped, smaller than the stem leaves (FNA 2014; Lawton 1971).

Leaf Cells: Medial laminal cells smooth (FNA 2014), longer and narrower than the basal cells; basal laminal cells frequently yellowish, porose and thick-walled (Lawton 1971); alar cells similar to adjacent cells (FNA 2014).

Diagnostic Characteristics
Rhytidiadelphus squarrosus, although very much alike in appearance to R. loreus, does not have pleated leaves and its somewhat swollen and rectangular alar cells are distinct from adjacent cells (Crum and Anderson et al. 1981). The alar cells are similar to adjacent cells in R. loreus (FNA 2014).

Range Comments
North American Range

Rare in areas other than close to the coast. Canada: BC, QC to NL and NS (except unknown in PE); USA: AK, WA to CA, ID and MT (FNA 2014). Known in Montana from Flathead, Gallatin, Glacier, Mineral, and Sanders Counties (Elliott and Pipp 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)

Often on rotting wood, also carpeting soil and humus, stones, and tree bottoms (FNA 2014), forest litter (Lawton 1971), in damp evergreen forests (FNA 2014). Occurring from lowlands to about 3280 feet (FNA 2014).

Reproductive Characteristics
Dioicous with female plants resembling male plants. Seta 15-50 mm tall (Lawton 1971), smooth. Capsule level, sometimes reaching 2.5 mm in length (FNA 2014), russet, creased or pleated when dry; exostome russet (Lawton 1971) with transverse fine lines or a network of them below; endostome processes with wide openings on the keel. Calyptra draping, cowl-like, smooth and hairless (FNA 2014).

  • 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. 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.
    • Vitt, D. J. Marsh, and R. Bovey. 1988. Mosses, Lichens & Ferns of Northwest North America. Seattle, WA: University of Washington Press. 296 p.
  • 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:
Rambling Round-headed Mountain Moss — Rhytidiadelphus loreus.  Montana Field Guide.  .  Retrieved on , from