SPECIES FACT SHEET
Common Name: Blytt’s thyme-moss, Blytt’s calcareous moss
Scientific Name: Mnium blyttii Bruch & Schimp.
Recent synonyms: none
Division: Bryophyta
Class: Bryopsida
Order: Bryales
Family: Bryaceae
Taxonomic Note: none
Technical Description: Plants small, light to dark green tufts, stems
reddish, from 1–4 cm tall matted with reddish brown rhizoids; leaves
densely clustered, ovate to elliptic-ovate, 2.5–3.5 mm long, apex, acute or
broadly rounded, shortly mucronate; margins bordered with 1–2 rows of
long narrow cells, bistratose, plane, entire or slightly denticulate with
teeth occasionally in pairs in the upper part; costa reddish, ending below
the apex; median leaf cells quadrate, shortly rectangular, thin walled, not
pitted, 20–35 µm, ± slightly thickened with rounded angles; basal cells
more elongated, oblong. Dioicous; sporophytes rare, horizontal to
pendent, ovoid to short-cylindric, slightly zygomorphic, 3–4 mm long;
peristome teeth double, papillose; spores 17–22 µm, mature in late
summer.
Distinctive characters: (1) quadrate to shortly rectangular thin walled
upper medial cells, and (2) cells lacking pits.
Similar species: Mnium arizonicum could be confused with M. blyttii but
is separated by having rhomboidal, thick walled and pitted leaf cells.
Other descriptions and illustrations: Flowers (1973), Lawton (1971)
Nyholm (1958)
Life History: Specific details for this species are not well documented.
In general the protonema, spore germination an development are typical
of all mosses. Male plants form an antheridial disk at the top of the stem
which is easily seen in the field. According to Flowers (1973), Schofield
(1976), Spence (1986) sporophytes are very rare in this species. Because
bryophyte spores are wind dispersed the lack of sporophytes could limit
the distribution of the species and be contributing to this species being
rare to uncommon in western North America.
Range, Distribution, and Abundance: Mnium blyttii is known from
Europe, Northern Asia, and Greenland. In the Pacific Northwestern North
America it is found in Alaska, Alberta, British Columbia, California,
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Colorado, Idaho, Montana, Oregon, Utah, Washington, Wyoming, and
Yukon.
Oregon Natural Heritage Information Center reports Mnium blyttii from
Baker, Union and Wallowa Counties in the Blue Mountain Ecoregion.
BLM: Suspected on Burns and Vale Districts.
USFS: Documented on the Walla-Whitman NF, suspected on the
Umatilla and Malheur National Forests.
Other: Olympic National Park
Spence (1986) comments, that M. blyttii was uncommon in both British
Columbia and Washington. In Colorado, Weber & Wittman (2007) state
that M. blyttii is “quite uncommon”.
Habitat Associations: Mnium blyttii occurs in seepage areas along
streamlets in subalpine and alpine areas. Spence (1986) reports it from
basic moist soil in exposed to protected sties in alpine areas. Label
information from historic collections includes: on damp soil over rock;
under Juniperus communis on dry soil, north slope of mountain, along a
wet ravine; in an alpine area along a stream at a calcite rock dome, on
shaded rock ledge of cave-like recess. Nyholm (1958), states that M.
blyttii occurs on calcareous, often humus-rich soil in mountains.
Threats: Mineral exploration or mining in calcium rich areas could be a
threat to this species. Recreation activities such as hiking and mountain
climbing might alter habitat needed for this species. Trail maintance and
construction could impact known populations.
Conservation Considerations: Consider additional surveys in suitable
alpine and subalpine habitats to look for new populations in the vicinity
of known sites. Because this species is small and occurs in higher
elevations it is probably under-collected which could be contributing to
its rarity. Consider re-routing trails or activities to avoid impacts to
known sites.
Conservation Rankings and Status:
Global: G5, Oregon (S1), British Columbia (S3S4), Alberta (S3), Colorado
(S1S3)
Oregon: ORNHIC List 3
Washington: Not ranked
BLM/USFS Strategic Species in Oregon
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Preparer: Judith A. Harpel Ph.D.
Date Completed: October 2008
Edited by: Rob Huff, March 2009
Revised by Candace Fallon, February 2011
(Revision only adds Attachment 1, Photos)
ATTACHMENTS:
(1)
Photos
References:
Flowers, S. 1973. Mosses of Utah and the West. Brigham Young
University Press. Provo, Utah. 567 pp.
Lawton, E. 1971. Moss Flora of the Pacific Northwest. The Hattori
Botanical Laboratory. Nichinan, Miyazaki, Japan. 362 pp.
NatureServe Explorer. 2008. An Online Encyclopedia of Life.
http://www.natureserve.org/explorer/
Nyholm, E. 1958. Illustrated Moss Flora of Fennoscandia, II. Musci.
Fasc. 3. Ed. by The Botanical Society of Lund. GWK Gleerup.
Lund, Sweden. 189-288.
Schofield, W. 1976. Bryophytes of British Columbia III: habitat and
distributional information for selected mosses. Syesis 9: 317-354.
Spence, J. 1986. Biogeography of the Montane Moss Flora of
Southwestern British Columbia and Northwestern Washington
State. unpublished Thesis. University of British Columbia.
Vancouver, British Columbia. 633 pp.
Weber, W. & R. Wittmann. 2007. Bryophytes of Colorado, Mosses,
Liverworts, and Hornworts. Pilgrims Process, Inc. Santa Fe, New
Mexico. 231 pp.
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Attachment 1 – Photos
All photos by J. Harpel, under contract with the Oregon/Washington Bureau of Land
Management.
Aral and basal cells
Upper medial cells
Leaf margin cells
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Leaf
Leaf apex
Leaf cross section
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Whole mount dry
Whole mount wet
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