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A Ptychostomum Moss - Ptychostomum weigelii
Other Names:  Bryum weigelii

Native Species

Global Rank: G5
State Rank: SNR

Agency Status
MNPS Threat Rank:

External Links

General Description
Plants: Acrocarpous. Growing in open tufts (Lawton 1971) or large, open patches of erect shoots, green or seldom pale red above (FNA 2014), brown below (Lawton 1971). Stems mostly 20-40 mm (FNA 2014), occasionally forked, radiculose (Lawton 1971); fertile branches with leaves dense at the top of the stem (comose) (FNA 2014).

Leaves: Openly spaced on the stem (except at the top), strongly twisted and curved to contracted when dry, upright to spreading somewhat when wet, green, sometimes with yellow tones, or seldom pale red, 1-3 mm in length (FNA 2014), 1 mm in width (Lawton 1971), lance-shaped, tending toward egg-shaped (FNA 2014) to widely so (Lawton 1971), plane, not enlarged at the top of the stem; base most often green, extending down the stem almost to the next leaf below; margins curved back and downward below, flat above, faintly bordered (FNA 2014), smooth (Lawton 1971); costa subpercurrent to extending a little beyond the apex and forming a narrow awn (FNA 2014).

Leaf Cells: Border of 1 or sometimes 2 rows of longer cells, parts of the proximal border 2-layered; lower laminal cells quadrangular to 6-sided, 3-4:1; medial and upper laminal cells quadrangular to 6-sided, 2-3:1 (FNA 2014).

Fruit ripens in summer (FNA 2014).

Diagnostic Characteristics
Bryum cyclophyllum and B. turbinatum resemble B. weigelii, but are very shortly or not decurrent (FNA 2014).

Range Comments
North American Range

AK to NL and NS, western coastal states of the US e to MT, WY, CO, and NM, ND to MI, OH, PA, WV and VA, northeastern states of CT, NH, VT and ME (FNA 2014). Known in Montana from Carbon, Flathead, Glacier, Jefferson, Missoula, Lewis and Clark, and Ravalli Counties (Elliott 2016).

Observations in Montana Natural Heritage Program Database
Number of Observations: 11

(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 rock and soil on stream banks, seepages around springs, banks along roads (Crum & Anderson et al. 1981), wetlands. Elevation: 0-11,480 feet (FNA 2014).

Reproductive Characteristics
Dioicous. Seldom producing capsules (Lawton 1971). Seta 20-40 mm tall (FNA 2014) or occasionally to 60 mm (Lawton 1971), russet. Capsule pear- or top-shaped, 3-4 mm in length, brown, the opening yellow (FNA 2014), shrunken below the opening when dry, drooping; neck not as long as the rest of the capsule (Lawton 1971); peristome fully developed; exostome dentitions yellow below, transparent above, without pores near the basal mid-line; endostome divisions with wide openings; cilia long and transversely ridged (FNA 2014), in 2’s or occasionally in 3’s (Crum & Anderson et al. 1981).

No specialized vegetative reproduction present (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.
  • Additional ReferencesLegend:   View Online Publication
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    • Flowers, S. 1973. Mosses: Utah and the West. Brigham Young University, Provo, Utah. 567 p.
    • 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.
    • Vitt, D. J. Marsh, and R. Bovey. 1988. Mosses, Lichens & Ferns of Northwest North America. Seattle, WA: University of Washington Press. 296 p.
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Citation for data on this website:
A Ptychostomum Moss — Ptychostomum weigelii.  Montana Field Guide.  .  Retrieved on , from