SPECIES FACT SHEET
Common Name: Alaska cedar-shake, Pacific featherwort (Edwards 2003)
Scientific Name: Plagiochila semidecurrens Lehm. et Lindenb. var. alaskana
(Evans) Inoue
Division: Marchantiophyta (incorrectly called Hepatophyta in U.S. government
taxon databases (e.g., ITIS 2008); see Stotler and Crandall-Stotler 2008)
Class: Jungermanniopsida
Order: Jungermanniales
Family: Plagiochilaceae
Taxonomic Note: Strongly urge accepting the recommendation made by
Wagner (Christy and Wagner 1996) that this be treated simply as the species,
thus including plants which some would treat as separate varieties (Hong
1992) but which Schofield and Godfrey (1979) called "minor subspecies" and
which Schofield later (2002) suggests lumping together. This recommendation
was acknowledged by Fredericks and Holmberg (2005), who note that any and
all varieties are equally rare in our region.
Technical Description: Leafy shoots ± erect-ascending, arising from a creeping
rhizomatous stem. Plants medium-sized, ca 2.5 mm wide; strikingly shiny
(especially when dry), dark golden-green to golden- brown. Rhizoids few,
scattered. Leaves succubously inserted, decurrent both antically and postically,
unlobed. Antical margin of leaf strongly reflexed while leaf insertion dips
downward at middle base, forming a convex antical fold and a longitudinal
groove up the center of the leaf. Leaves with a distinct vitta region at the
median base, i.e., with very numerous elongated cells, to 14–20 µm wide x 48–
90 µm long, averaging 4.2 x as long as wide. Leaf margins strongly dentate with
slender, cilia-like teeth, usually 17–23 per leaf (mean ca. 19), frequently 3–5(–7)
cells high, with the apical cell elongate, and (1)2–4 cells wide at the base.
Median cells 14–24(mean 18.2) µm wide; marginal cells 12–18 (mean 14.3) µm
wide. Underleaves vestigial. Gemmae absent. Sporophytes not observed in this
region. (After Godfrey [1977] with slight modification and rearrangement.)
Distinctive Characters: Erect shoots with asymmetrical leaves having a
distinctive trough or groove running up the middle of the leaves characterize
the genus.
Similar species: At greater than arm's length distance, species of Scapania
sometimes look like Plagiochila because of similar growth habit; up close the
bilobed, folded leaves of Scapania immediately rule it out. The only other
species of Plagiochila in the area, P. porelloides, has a dull leaf surface and
lacks the prominent group of elongated cells at leaf base (vitta) of P.
semidecurrens. Plagiochila semidecurrens also has very large, bulging trigones
while P. porelloides has only moderately enlarged trigones (Hong 1992, where P.
porelloides is treated as P. satoi and P. asplenioides).
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Life History: Published studies of life history traits in this particular species
have not been detected. This species is perennial, visible whenever the
substrate is exposed. Plants are best identifiable when fertile, at the end of the
growing season. However, sporophytes appear to be rarely produced, Godfrey
(1977) having never seen any in her study of the species in southwestern
British Columbia.
Range, Distribution, and Abundance: The range of Plagiochila semidecurrens
follows a North Pacific Arc, from eastern Asia to the Pacific Coast of North
America. It is relatively abundant in Alaska and northern British Columbia,
becomes less frequent in southwest British Columbia, and is found in the
conterminous United States only in Saddle Mountain State Park, Clatsop
County, Oregon.
BLM: Not expected on any BLM district.
USFS: Suspected in Siuslaw and Olympic National Forests.
Habitat Associations: "The species shows a diverse ecology, occurring
abundantly on cliffs and banks of humid canyons, particularly near waterfalls,
on maritime exposed cliffs, on tundra cliffs and as an epiphyte, particularly on
Chamaecyparis and Pinus, where it forms thick sheaths up the tree base."
Schofield (1968). Fredericks and Holmberg (2005) mention a communication
from Schofield that the Saddle Mountain population was found on a north
facing basalt outcrop at 750 m (2470 feet).
Threats: Beyond recognizing possible changes in habitat due to global
warming, threats in remote parts of Saddle Mountain State Park are not easily
ascertained.
Conservation Considerations: A general discussion of conservation issues is
found in Fredericks and Holmberg (2005). See also the Conservation
Assessment for Radula brunnea, another species known in the Pacific
Northwest only from Saddle Mountain State Park (Fredericks, et al. 2005). At
present, management of the known sites fall under the aegis of the Oregon
state park system. Their responsibility should be acknowledged and given
ongoing encouragement. If new sites are found in Washington or Oregon,
careful attention should be given to their management.
Conservation Rankings and Status:
Global: G4T3; Oregon: SH (H=Historical occurrence)
(The Oregon Natural Heritage Information Center ranking of SH should be
revised to S1, since there is a site known in Oregon).
ORNHIC List 2
Washington: Not ranked
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USFS Strategic Species in Oregon
Other pertinent information:
Surveys and Survey Protocol: Basaltic hill and ridge tops similar to Saddle
Mountain in the coast ranges of Washington and Oregon could be explored.
Key to Identification of the Species: Christy and Wagner 1996.
Preparer: David H. Wagner
Edited by: Rob Huff
Date Completed: October, 2008
Updated in June 2009 by Candace Fallon (Update added Attachment 1, Photos,
to the Species Fact Sheet).
ATTACHMENTS:
(1)
Photos
References:
Christy, J.A. & D.H. Wagner. 1996. Guide for the identification of rare,
threatened or sensitive bryophytes in the range of the northern spotted
owl, western Washington, western Oregon and northwestern California.
USDI Bureau of Land Management, Oregon-Washington State Office,
Portland. 222 pp.
Edwards, S.R. 2003. English Names for British Bryophytes. Third Edition.
British Bryological Society Special Volume No. 5.
Fredricks, N. and L. Holmberg. 2005a. Conservation Assessment for Alaska
cedarshake Plagiochila semidecurrens Lehm. & Lindenb. var. alaskana
(Evans) H. Inoue. Unpublished report prepared for USDA Forest Service
Region 6 and USDI Bureau of Land Management, Oregon and
Washington.
Fredricks, N., R. Lesher, J. Harpel and L. Holmberg. 2005b. Conservation
Assessment for brown flatwort Radula brunnea Steph. Unpublished
report prepared for USDA Forest Service Region 6 and USDI Bureau of
Land Management, Oregon and Washington.
Godfrey, J.D. 1977. The Hepaticae and Anthocerotae of Southwestern British
Columbia. Unpublished Ph.D. dissertation on file at the library,
University of British Columbia, Vancouver, B.C., Canada.
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Hong, W.S. 1992. Plagiochila in Western North America. The Bryologist 95: 42147
ITIS. 2008. Integrated Taxonomic Information System (official government
database of scientific names) http://www.itis.gov/index.html Accessed
August 2008.
Oregon Natural Heritage Information Center. 2007. Rare, threatened and
endangered species of Oregon. Oregon Natural Heritage Information
Center, Oregon State University. Portland. 100 pp.
http://oregonstate.edu/ornhic/2007_t&e_book.pdf
Schofield, W.B. 1968. Bryophytes of British Columbia II Hepatics of particular
interest. Journal of the Hattori Bot. Lab. 31: 265-282.
Schofield, W. 2002. Field Guide to Liverwort Genera of Pacific North America.
University of Washington Press, Seattle, Washington, U.S.A.
Schofield, W.B. and J.D. Godfrey. 1979. Radula brunnea from western North
America. Jour. Hattori Bot. Lab. 46: 285–288.
Stotler, R.E. and B. Crandall-Stotler. 2008. Correct author citations for some
upper rank names of liverworts (Marchantiophyta). Taxon 57: 289-292.
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Attachment 1 – Photos
These photos represent the species Plagiochila semidecurrens, not necessarily the variety
alaskana. All photos by Dr. David Wagner, under contract with the Oregon/Washington
Bureau of Land Management.
Leaf
Leaf margin
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Shoot tip
Shoot tip reflected light
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