SPECIES FACT SHEET
Common Name: Largeleaf fissidens moss
Scientific Name: Fissidens grandifrons
Division: Bryophyta
Class: Bryopsida
Order: Fissidentales
Family: Fissidentaceae
Technical Description: Shoots dark green to blackish toward base,
simple or branched, 2-3.5 mm wide, to 12 cm long, sometimes encrusted
with lime. Stems sometimes matted with brown rhizoids toward base.
Leaves 3-4.5 x 0.4-0.7 mm, rigid and overlapping, arranged in two ranks
and flattened in one plane, their tips usually curved under when dry, 2-7
layers of cells thick in section (multistratose) except for single layer of
marginal cells, with a strong costa, entire to crenulate margins, and no
border of differentiated cells. The lower 1/2 - 2/3 of each leaf has a
distinctive overlapping but separate layer of tissue (vaginant lamina) on
one side of the costa, forming in cross section a flattened Y shape with
the costa located at the junction of the three limbs. Stem often
conspicuous near tips of shoots as a white line between the two ranks of
leaves. Capsules unknown in North America. Distinctive characters:
(1) Large, robust species of Fissidens with stiff, dark green or blackish
shoots 3 or more cm long, (2) leaves multistratose in section except for
single layer of marginal cells, (3) in areas with calcareous or serpentine
bedrock geology. Similar species: Other species of Fissidens have leaves
bordered by differentiated cells, or the leaves are unistratose. Other
descriptions and illustrations: Crum 1983: 55; Crum & Anderson
1981: 111; Lawton 1971: 46; Sharp et al. 1994: 80.
Life History: Details for this species not documented. Protonema
inconspicuous, forming buds and shoots in usual fashion of moss growth
and development. Because capsules are unknown in North America,
reproduction and dispersal are accomplished by vegetative
fragmentation.
Range, Distribution, and Abundance: Circumboreal, south to Central
America. In all northwestern states and California.
Documented on: National Forests: Rogue River-Siskiyou, WallowaWhitman. BLM Districts: Medford.
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Uncommon to rare in Oregon and Washington because of scarcity of
calcareous and other basic bedrock (Brooks 1989).
Habitat Associations: Forming dense mats on rocks in streams, on cliff
faces, concrete, or rarely on soil. Plants submerged or in spray zone,
usually but not always on carbonate or other basic rocks. Elevation from
lowlands to 4500 feet. In Oregon and Washington, it occurs mostly on
limestone, marble, or serpentine, and occasionally in calcareous seepage
cracks in fractured basalt. Fissidens grandifrons is one of a suite of
mosses that are largely limited to wet, carbonate-rich substrates in
Oregon and Washington that includes Eucladium verticillatum,
Gymnostomum species and Crumia latifolia.
Threats: Road construction, recreational climbing in streambeds
(canyoning or canyoneering) and upstream activities such as logging,
road construction, and dredging that cause excessive siltation could be
detrimental. Water diversion would probably decimate populations.
Because of wetland regulations, quarrying of limestone, marble, and
serpentine in streambeds seems only a remote threat. Riparian buffers
should adequately protect most populations.
Conservation Considerations: Relative rarity of carbonate or other
base-rich bedrock makes this species rare in Oregon. Consider
managing known sites at least until its abundance on calcareous rock
and serpentine is better understood. Many limestone sites on private
land have already been quarried (Brooks 1989).
Preparer: John A. Christy
Date Completed: May 2006
References
Brooks, H.C. 1989. Limestone deposits in Oregon. Oregon Department
of Geology and Mineral Industries Special Paper 19: 1-72.
Crum, H. 1983. Mosses of the Great Lakes Forest. 3rd edition.
University of Michigan Herbarium, Ann Arbor. 417 pp.
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_______ & L.E. Anderson. 1981. Mosses of Eastern North America. 2
volumes. Columbia University Press, New York. 1328 pp.
Lawton, E. 1971. Moss Flora of the Pacific Northwest. Hattori Botanical
Laboratory, Nichinan, Japan. 362 pp.
Oregon Natural Heritage Information Center. 2004. Rare, threatened and
endangered species of Oregon. Oregon Natural Heritage Information
Center, Oregon State University. Portland. 104 pp.
http://oregonstate.edu/ornhic/2004_t&e_book.pdf
Pursell, R.A. 2005. Fissidentaceae. Bryophyte Flora of North America,
Provisional Publication, Missouri Botanical Garden.
http://www.mobot.org/plantscience/bfna/V1/FissFissidentaceae.ht
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Sharp, A.J., H. Crum & P.M. Eckel (eds). 1994. The Moss Flora of
Mexico. 2 volumes. Memoirs of the New York Botanical Garden 69: 11113.
Washington Natural Heritage Program. 2005. Working list of rare
mosses.
http://www.dnr.wa.gov/nhp/refdesk/lists/ mosses.html
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