Abstract
A population of Scapania scandica (Arn. & Buch) Macvicar discovered in Curry County, Oregon on a near-shore sea stack is discussed and illustrated with photographs via the internet. The constellation of diagnostic characters closely matches published descriptions of Scapania scandica. Other possible diagnoses can be eliminated by the condition of one or more critical characters. S. scandica has not been previously found in the Pacific Northwest south of latitude 48°N, but its occurrence on the Oregon coast near latitude 42°N is consistent with the biogeographic distributions of other rare bryophytes and lichens. The biogeographic significance of sea stack and rocky headland mesohabitats is briefly reviewed.

Introduction
Scapania is a notoriously difficult taxonomic knot (Schuster, 1974, pp. 232-245). Diagnostic character suites lack coherence in many of the genotypically variable lineages and species limits are further confounded by copious phenotypic plasticity. The taxonomic result is such breadth in species descriptions for some taxa that phenotypic gaps are frequently obscure, and in some cases apparently nonexistent. The problem is further complicated by the fact that key diagnostic features associated with sexual reproduction (e.g. perianth morphology) are often unavailable in populations occupying extremes of environmental tolerances for a lineage, where sexuality is not expressed. Populations near the periphery of geographic distribution that are both sterile and express extreme phenotypes can be almost indeterminable. Keys, which by their very nature assert discrete phenotypic gaps, simply do not work for specimens outside the narrowly defined norms used for taxa included in the key.

Descriptions of known geographic distribution can serve as a guide, but in areas where range extensions are plausible or expected, known range is not much help, and may in fact bias determinations in favor of taxa known to occur regionally. Reliance on range descriptions to sway identifications could actually hinder close examination of critical plants. In any case, the tangled morass of morphological descriptions that must be comprehended for a clear determination is daunting for any but the most distinctive taxa in Scapania may have discouraged progress in documenting the distributions of some lineages.

Scapania scandica (Arn. & Buch) Macvicar is one such diffusely bounded taxon that is relatively little known. The overlap of phenotypic expression between S. scandica, S. mucronata, S. undulata var. oakesii, and dwarfed S. americana presents a predicament requiring careful consideration of the distinguishing constellations of character expression found in each for a reasonably certain diagnosis of any in this group. Of course, the full characteristic expression of any one of these taxa, all of which occur in the Pacific Northwest, is not problematic, but, as is often the case in Scapania, populations of these taxa with individuals on the phenotypic fringe are frequently encountered. The purpose of this report is to document a range extension for S. scandica, and to elucidate both the diagnostic characters of the species and those character states that eliminate other possible diagnoses.

Sea stacks on the Pacific Northwest coast have never been thoroughly surveyed for rare cryptogams. Oregon coast sea stacks combine critical mesohabitat features and geographic position in ways that predict a high incidence of rare cryptogams. The discovery of S. scandica on a relatively small near-shore sea stack hints that larger and more completely insular sea stacks may harbor a high incidence of disjunct populations. This report initiates a series dedicated to documenting the terrestrial cryptogamic flora of Pacific Northwest sea stacks and peninsular rocky headlands.

Specimen Collection
The specimen (Jessup 17-89, deposited in SOC) was collected on a near-shore sea stack at 42°3’56" N, 124°18’47" (NAD-1983) on vertical NNE-facing metabasalt above a narrow ledge at an elevation of approximately 30 m directly above sheltered intertidal rocks. The foot of the sea stack was approached on foot through the intertidal zone at low tide, and the site was accessed by free climbing the seaward face then crossing the ridge to the sheer north face and traversing along a narrow ledge. The climb was generally a class-3 route but involved class-4 maneuvers in a few places to reach the ledge. The most serious exposure occurred during class-4 moves near the ridgeline where wind, focused by the seaward bluff, was a gusty 40 knots. The collection site is shaded from direct sun but receives strong indirect light. Although the collection site is somewhat sheltered from exposure to direct wind, the entire sea stack mesohabitat is subject to a strong diurnal sea breeze and frequent summer morning fog and drizzle. The site is well above the intertidal spray zone, though blown spray likely wets the entire sea stack during winter storms.

The dominant associated hepatic species at the site are Marsupella emarginata, Porella navicularis, Cephaloziella byssacea, and Frullania franciscana, all of which combine to form a nearly continuous cover on vertical rock faces at the collection site. Species found in small amounts in crevices on the same rock face include Lophocolea cuspidata and Radula bolanderi. The Scapania in question was found initially as scattered isolated shoots in pure patches of Marsupella emarginata and, on closer inspection, as small (1-2 cm²) colonies of loosely aggregated plants growing within and on the margins of otherwise pure patches of Cephaloziella byssacea. The Scapania was not found outside of intimate association with other hepatics -- all were growing within dense hepatic associules over fine textured metabasalt.

Specimen description
Plants uniformly small with shoots (0.3)0.5-1.0(1.2)mm wide, by (5)6-10(15)mm long. Stems on the largest plants 170--180min diameter, the cortex uniformly of 1--2 differentiated cell layers, not at all flattened, with open lumens, the walls deep reddish brown, branches infrequent, laterally or ventrally intercalary. Rhizoids few, short, sparsely distributed along stem but absent near the apex. Leaves distally greenish to golden yellow-brown, adaxially red-brown to occasionally, under higher magnification, with a clear blush of red, and adaxially deeply vinaceous near the bases. Leaf margins evenly spinose denticulate in the distal ½--¾ on both dorsal and ventral lobes of all upper leaves, the teeth 1-2(3) cells high and typically 1-2 cells broad at base, the apical tooth sometimes somewhat larger, forming a slight mucro. Lower leaves occasionally edentate or with just a few scattered teeth. Keel .45--.55 the length of the ventral lobe, slightly arched to nearly straight, not at all winged or toothed, 1-2 stratose throughout. Ventral lobes subtransversely inserted, the line of insertion forming a slight to distinct arch, the postical margin not at all decurrent to slightly decurrent to level of keel insertion or just below keel insertion. Lobes ovate to obovate, the width approximately .7x the length, broadly rounded apically, not at all accuminate, though occasionally with a prominent apical tooth. Dorsal lobes transversely inserted, not at all decurrent. Lobes ovate, the width .7--.9x the length, the upper leaves broadly rounded apically to somewhat obtuse or occasionally acute on the lower leaves, frequently with a prominent apical tooth. Both dorsal and ventral lobes erect spreading to nearly squarrose at the apex, abaxially slightly concave, somewhat reflexed in the distal ¼, with a narrow zone of slight recurvature along the margin on dried plants. Leaf cells not discernably differentiated along the laminal margin, the walls uniformly thickened throughout, cell diameter averaging 15mat the margins to 25mnear the lobe bases. Cuticle distinctly fine to roughly verrucose throughout, the laminal cells with obvious large papillae in surface view when imaged with phase interference microscopy. Trigones weakly convex to more often flat or somewhat concave, not at all bulging. Oil bodies 2-4(5) per cell, round to ovate, 2.5--5.0mwide by 2.5--6.0(7.0)mlong, clear and finely granular. Gemmae abundantly produced on almost all plants observed, uniformly 2-celled, elliptic to oval or ovate, almost entirely deep pink-red to vineaceous, tending to colorless in a few plants, 12--15mwide x 20--23mlong, the upper leaves occasionally eroded through gemmae production leaving jagged crescent sinuses along the lobe margins. Sexual reproductive structures not found on any plants in the collection.

Diagnosis
The plants readily key to S. scandica without much trouble using keys in both Schuster (1974, pp. 245-268, 363-365) and in Hong's treatment of western North American Scapania (Hong, 1980), and are a good fit to the published description (Schuster, 1974). Since S. scandica has not been previously reported from Oregon, or, for that matter, anywhere else in western North America below 48°N, it is prudent to carefully compare the specimen with descriptions of taxa that are known from southern Oregon, especially given Schuster's discouraging words about the lack of crispness in species boundaries for this taxon. It at first seemed to me the specimen might be conveniently shoehorned into any one of several taxa known to occur in the region. Given the breadth of descriptions in Schuster (1974), S. mucronata, S. undulata var. oakseii, and a dwarfed expression of S. american might all accomodate the specimen. Descriptions of several other taxa, including S. helvetica, S. mucronata var. praetervisa, S. curta, S. ligulata, and S. parvifolia were also considered in detail. After careful study of the specimen, however, it became apparent that, in spite of a broad overlap in phenotypic expression of the candidate taxa, none but S. scandica could adequately account for the particular constellation of characters observed.

Specifically, the specimen is immediatly separable from S. mucronata (including S. mucronata var. praetervisa) by a strong tendency in S. scandica for ventral leaf lobes to be broadly rounded rather than acute and +/- mucronate, for ventral leaf lobes to develop a reddish pigmentation basally, and by strong dentition of leaf lobes associated with gemmiparous shoots.

The specimen is separable from S. undulata by consistently transverse to short-decurrent insertion of ventral lobes, absence of distinctly differentiated cells bordering leaf lamina, the relatively large oil bodies obscuring most of the lumen, and presence of pronounced cuticular papillae. In addition, the specimen is distinct from S. undulata var. oaksii in the complete absence of a wing and teeth on the keel.

The specimen is separable from dwarf forms of S. americana by dorsal lobes clearly and consistently transversely inserted (not at all succubous), complete absence of paraphyllia, absence of dorsiventral differentiation of stem as seen in cross section, cortical cells that are neither flattened nor have wall thickness exceeding the lumen diameter, stems are deep red-brown, not blackish, and the terminal cell of leaf teeth are often 3-5x as long as wide (Schuster, 1974, pg. 586).

Discussion
Hong (1978a) included ten taxa of Scapania in his list of Oregon hepatics. Christy and Wagner (1996) report two additional taxa from Oregon. Overall, 25 taxa of Scapania are currently known from the Pacific Northwest defined as British Columbia, Washington, and Oregon (Godfrey, 1977; Godfrey & Godfrey, 1978; Godfrey & Schofield, 1979; Hong, 1978a, 1978b, 1980a, 1980b, 1981; Christy & Wagner, 1996). In published reports S. scandica is only documented in western North America from British Columbia and Alaska (Hong, 1989). A search of UBC herbarium records reveals several specimens that add significant detail to our knowledge of the range of S. scandica in the Pacific Northwest. The following representative collections documenting S. scandica in the Pacific Northwest are all in UBC. While these collections were  not examined specifically for this report, the determinations are all on good authority.

British Columbia: Mt. Cheam, above Agassiz, ca. 49°15'N 121°40'W, W.B. Schofield 76941; Long Beach, Pacific Rim N.P., Vancouver Is., J.D. Godfrey 2708; Flower Ridge trail, Strathcona N.P., J.D. Godfrey 1307; Whistler Mt., J.D. Godfrey 2107; Joffre Mt., e. of Pemberton, J.D. Godfrey 2085; Elk Mt. trail, vic. Chilliwack, J.D. Godfrey 1196; vic. Lindeman Lake, Chilliwack River valley, J.D. Godfrey 2605.  Washington: Washington Pass Bog, North Cascades, ca. 48°N 121°W, J. Spence 1138; Church Mt. trail, Mt. Baker Snoqualmie N.F., ca. 49°N 121°50'W, J.D. Godfrey 2983.

The known geographic range in the Pacific Northwest (Map 1), including previously published reports (Hong, 1980) extends from Saint Matthew Island in the Bering Sea, eastward in the Aleutian Archipelago to Unalaska Island, from Kodiak Island in the Gulf of Alaska, mainland Alaska in the Alaska Range, southward in the Alexander Archipelago on Baronof Island, on Vancouver Island and the southern coast of British Columbia, inland in southern British Columbia at least as far as Joffre Mt. and in the Chilliwack River valley, south in the Western Cordillera as far as the Northern Cascades in Washington, and at one isolated station on the southern Oregon coast (this report).

While the southern Oregon collection represents a substantial range extension, the occurrence of S. scandica on the Oregon coast is not unexpected. The Oregon coast and coastal mountains are known for the high incidence of species represented by populations at the southern limit of their range. Among hepatics, Diplophyllum albicans, Diplophyllum plicatum, Kurzia makinoana, and Metzgeria temperata, taxa with otherwise boreal or North Pacific Arc distributions, all occur as extreme southern populations on the immediate coast and near coastal mountains in Oregon and northern California (Christy & Wagner, 1996). Bryophytes associated with Sphagnum are particularly well represented among taxa range limits along the Oregon coast. Calypogeia sphagnicola, Cephaloziella spinigera, Lophozia laxa, Pohlia sphagnicola, and Polytrichum strictum, all primarily boreal plants associated with Sphagnum, reach the southern extremes of their distributions on the Oregon coast. Other rare bryophytes show up on the Oregon coast as long range disjuncts or local endemics presumably derived through long range founders. Included in this group are Campylopus schmidii and Libella fryei. Lichens demonstrate a similar pattern of attenuate distributions and disjunctions on the immediate coast of Oregon (McCune, Rosentreter & Debolt, 1997) where taxa such as Anaptychia setifera and Bryoria bicolor are found as isolated populations on rocky headlands and near-coast mountaintops.

In general, exposed rocky headlands and near-coast summits harbor the greatest concenrations of rare disjuncts and populations at the limits of geographic distribution. Many are primarily circumboreal with prominent range extensions southward at high elevations in the western cordillera, but a significant percentage reach their southern limit on the immediate coast. This pattern is perhaps nowhere more pronounced than on Saddle Mountain in Clatsop County, Oregon. Known disjunct hepatics there include Lophozia barbata, Lophozia lycopodioides, Herbertus aduncus, Herbertus sakuraii, Plagiochila semidecurrens var. alaskana, Radula brunnea, Radula obtusiloba ssp. polyclada, and Tritomaria quinquedentata (Christy & Wagner, 1996). Known disjunct populations of mosses on Saddle Mountain include Encalypta brevipes, Iwatsukiella leucotricha, and Rhytidium rugosum. Disjunct lichens there include Sticta arctica, Bryoria bicolor, Hypogymnia duplicata, and Ochrolechia subplicans. A similar concentration of disjunct lichens is reported from other near-coast summits and rocky headlands (McCune, Rosentreter & DeBolt, 1997). A similar pattern of near-coast disjuncts and range limits is repeated in Washington and British Columbia where, among other extreme pacific arc disjuncts, occur taxa such as Takakia lepidozioides, Porella fauriei, Radula obtusiloba ssp. polyclada, Dendrobazzania griffithiana, Cololejeunea macounii (Hong, 1987), and even Sphenolobopsis (Schofield, 1968). Detailed discussion and explication of Pacific coast biogeography of cryptogams is addressed in Schofield (1968, 1984), Hong (1987), and Norris (1997).

Oregon coast sea stacks have a combination of mesohabitat attributes and geographic position that endows them with the potential for a high incidence of rare taxa. Sea stacks are ancient remnants of headlands left standing isolated from the shore after surrounding rocks have eroded. The sea stack mesohabitat closely simulates summer climatic conditions obtaining at much higher latitudes and further inland at higher elevations. The rocky and cliffy mesohabitat of prominent headlands and sea stacks also provides a rich assemblege of microhabitats similar to those found in rocky and cliffy montane and alpine mesohabitats (Vitt & Belland, 1997). Sea stacks are thus predicted to harbor an unusually high concentration of rare cryptogams. These ancient fragments of landscape, climatically buffered by their isolation from the mainland and relatively immune from human disturbances, are consequently likely targets in a search for rare cryptogams. Taxa distributed primarily at high latitudes find a narrow zone of suitable habitat extending southward along the coast, and once established, given the relative stability of the mesohabitat, are likely to persist. While some of the rare disjuncts may have arrived by long distance dispersal, it seems likely that others persist as relicts in a narrow refugial zone following the post-pleistocene retreat of a broad periglacial climatic belt.

Significant concentrations of rare cryptogams have come to light in recent years through a search of on-shore sites having some of the attributes of sea stacks. It seems likely that additional rarities await discovery on prominent sea stacks as well. Most are perhaps confined to specific microhabitats that are both spatially fragmented and restricted in area, and only a small percentage of such available sites can be expected to harbor colonies of rare taxa. The logistical difficulties and significant perils encountered in searching and retrieving specimens from cliffs and ledges on sea stacks, however, does not bode well for their quick and easy discovery. Among sea cliff sites harboring rare taxa, only a small percentage will ever be accessible for collection. Though a few new taxa, such as Scapania scandica, will turn up periodically, most will certainly remain undiscovered for a long time to come. Nevertheless, a concerted effort to study cryptogams of west coast sea stacks and rocky headlands promises to be highly rewarding.

Acknowledgments
I wish to thank Southern Oregon University for a series of grants supporting development of a photomicrography facility at the SOU Herbarium, and for generous provision of the server space needed to host bryophyte image pages. Thanks are also extended to Dr. Wilf Schofield,  Dr. Judith Godfrey and  Dr. John Spence for permission to document their unpublished collections.

Literature Cited
Christy, J. A. and 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. BLM - Oregon-Washington State Office, Portland.

Godfrey, J. D. 1977. New and interesting hepatics from British Columbia, Canada, and northern Washington State, U.S.A. I. Bryologist 80(3): 539-543.

Godfrey, J. D. and G. A. Godfrey 1978. Scapania hians in Shensi, China and British Columbia, Canada. Bryologist 81(3): 357-376.

Godfrey, J. D. and W. B. Schofield 1979. New and interesting hepatics from British Columbia, Canada, and northern Washington State, U.S.A. II. Bryologist 82(2): 162-170.

Hong, W. S. 1978a. Preliminary assessment of the hepatic flora of Oregon. Bryologist 81(3): 437-442.

Hong, W. S. 1978b. Hepaticae of northeastern Washington. Bryologist 81(4): 586-589.

Hong, W. S. 1980a. The genus Scapania in western North America. II. Taxonomic treatment. Bryologist 83(1): 40-59.

Hong, W. S. 1980b. Hepaticae of the North Cascades Range, Washington. Bryologist 83(1): 94-102.

Hong, W. S. 1981. Hepaticae of Wells Gray Provincial Park, British Columbia, Canada. Bryologist 84(3): 414-419.

Hong, W. S. 1987. The distribution of western North American Hepaticae. Endemic taxa and taxa with a north Pacific arc distribution. Bryologist 90(4): 344-361.

McCune, B., R. Rosentreter, and A. Debolt 1997. Biogeography of rare lichens from the coast of Oregon. In, T. N. Kaye, A. Liston, R. M. Love, D. L. Luoma, R. J. Meinke, and M. V. Wilson (eds.), Conservation and Management of Native Plants and Fungi. Native Plant Society of Oregon, Corvallis.

Norris, D. H. 1997. The Oregon-California border: important in bryogeography. J. Hattori Bot. Lab. 82: 185-189.

Schofield, W. B. 1968. Bryophytes of British Columbia II. Hepatics of particular interest. J. Hattori Bot. Lab. 31: 265-282.

Schofield, W. B. 1984. Bryogeography of the Pacific coast of North America. J. Hattori Bot. Lab. 55: 35-43.

Schuster, R. M. 1974. Hepaticae and Anthocerotae of North America East of the Hundredth Meridian, Volume III. New York.

Vitt, D. H. and R. J. Belland 1997. Attributes of rarity among Alberta mosses: patterns and predictions of species diversity. Bryologist 100(1): 1-12.

Map 1. Pacific Northwest distribution of Scapania scandica based on  published
reports and select herbarium records in the UBC online database.
 
 

Northwest face of sea stack harboring S. scandens.
 

Nascent sea stack headland at Ophir beach.
 

Cluster of sea stacks viewed from summit of Sebastian Head.
 

Sebastian Head.

Haystack Rock.
 

 
 

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Last revised on 7 August 2001

 Copyright © 2001 Steven L. Jessup, Southern Oregon University