SPECIES FACT SHEET
Common Name: Delicate Earth-moss
Scientific Name: Pseudephemerum nitidum (Hedw.) Loeske
Recent synonyms: Phascum nitidum Hedw.
Division: Bryophyta
Class: Bryopsida
Order: Dicranales
Family: Dicranaceae
Taxonomic Note: In the Bryophyte Flora of North America treatment, P.
nitidum has been placed in the family Ditrichaceae.
Technical Description: Plants very small up to 2 (5) mm tall, forming
scattered pale green to yellowish-brown patches; leaves lanceolate from
an ovate base, 1.8 mm long, erect-spreading; margins plane, entire,
serrulate at the apex; costa ending below the apex; upper medial cells
lax, thin-walled, rectangular to narrowly rectangular, 10–15 µm wide.
Synoicous, seta short, about 0.22 mm long; capsule pale brown,
immersed, 0.3–0.4 mm, ovoid with a short point; cleistocarpous; spores
20–32 µm, brown, papillose; pale brown to hyaline, smooth mulberryshaped, sub-spherical to oval rhizoidal tubers rarely occur.
Distinctive characters: (1) lax and undifferentiated leaf cells, (2)
serrulate leaf tips, and (3) smooth rhizoids.
Similar species: Sterile, young material of Pohlia, Bryum and
Leptobryum could be confused with P. nitidum but the above
characteristics separate it from these genera. Pleuridium, another genus
that could be confused with P. nitidum, is separated by having more
conspicuous capsules.
Other descriptions and illustrations: Lawton 1971; Yip 2005, 2007;
Smith 2004.
Life History: Specific details for this species are not well documented.
In general the protonema, spore germination and development are typical
of all mosses. According to Schofield (1976) and Smith (2004)
sporophyte are common. In England they are produced throughout the
year but are more common in late summer and autumn (Smith 2004).
Yip (1998) comments, that the axillary archegonia, mature sporophyte
and the related sheath are generally persistent on the older part of the
stem, thus appearing lateral when new shoots develop. The production
of rhizoidal tubers (Arts et al 1991) may be a dispersal mechanism for
this species.
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Range, Distribution, and Abundance: Pseudephemerum nitidum is
known from Europe, Asia, Africa, Madagascar, New Zealand, Tasmania,
Mexico and South America. In the Pacific Northwestern North America it
is only known from two locations, British Columbia and Oregon.
Oregon Natural Heritage Information Center reports Pseudephemerum
nitidum from Lane County in the Willamette Valley Ecoregion.
BLM: Documented on Eugene District
USFS: Not documented or suspected
Pseudephemerum nitidum is rare in North America and there are only two
known locations. According to Schofield (1968) the British Columbia site
has been “bulldozed”. Therefore the Oregon location is the only extant
population in North America. This species is common in most of
England and Wales but is rare or occasional elsewhere (Smith 2004).
Habitat Associations: Pseudephemerum nitidum occurs on damp clay or
silty soil. Label information from the only two sites in North America is
as follows: on silt hummocks in grassy area near river bank; on old
molehills in grassland, full exposure to partial shade, with Lomatium,
Horkelia and an algal soil crust, elevation 341 feet.
Threats: Urbanization may be the primary threat to this species. Trail,
road or dam construction in or around a known population could pose a
threat. Development of farming also may be a threat. Because it
appears that this species needs damp soil changes in hydrology could be
a threat.
Conservation Considerations: All known localities could be revisited to
determine the extent of the populations and characterize habitats. It
would be good to explore similar habitat to find new populations.
Conservation Rankings and Status:
Global: G4, Oregon (S1), British Columbia (SX)
Oregon: ORNHIC List 3
Washington: Not ranked
BLM Strategic Species in Oregon
Preparer: Judith A. Harpel Ph.D.
Date Completed: November 2008
Revised by Candace Fallon, February 2011
(Revision only adds Attachment 1, Photos)
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ATTACHMENTS:
(1)
Photos
References:
Arts, T. & S. Risse. 1991. Tubers in Pseudephemerum nitidum (Hedw.)
Reim. Lindbergia 17: 55-58.
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/
Ochyra, R. 1995. The correct author citation for Pseudephemerum
nitidum. Journal of Bryology 18(4): 829.
Schofield, W.B. 1968. Bryophytes of British Columbia I Mosses of
Particular Interest. The Journal of the Hattori Botanical
Laboratory 31: 205-226.
Schofield, W.B. 1976. Bryophytes of British Columbia III: habitat and
distributional information for selected mosses. Syesis 9: 317 –
354.
Smith, A. 2004. The Moss Flora of Britain and Ireland. Second Edition.
Cambridge University Press. Cambridge, England. 1012 pp.
Yip, K.L. 1998. The occurrence of Pseudephemerum nitidum (Hedw.)
Loeske in North America, with some interesting observations.
Evansia. 15(3): 112-114.
Yip, K.L. 2005. Pseudephemerum, New to the United States and Mexico.
The Bryologist 105: 256-258.
Yip, K. L. 2007. Pseudephemerum in Flora of North America North of
Mexico. Bryophyta Vol. 27 Part 1: 466-467. Oxford Univ. Press.
Oxford.
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Attachment 1 – Photos
All photos by J. Harpel, under contract with the Oregon/Washington Bureau of Land
Management.
Alar and basal cells
Upper medial cells (1)
Upper medial cells (2)
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Leaf
Leaf apex (1)
Leaf apex (2)
Leaf cross section
5
Whole mount (1)
Whole mount (2)
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