IV. Botrychium minganense Victorin

Area of Application: Throughout the area covered by the Northwest Forest Plan.

A. Introduction

Botrychium minganense is a small, herbaceous, perennial fern in the Ophioglossaceae plant family. Common names used for the species include Victorin's grape-fern and gray moonwort.

Botrychium minganense is classified as a Survey and Manage Component 1 and 2 species under the FSEIS/ROD (USDA Forest Service and USDI Bureau of Land Management 1994). Botrychium minganense is on the R6 Regional Forester's Sensitive Species List (USDA Forest Service 1991) and is considered an Oregon and Washington Assessment Sensitive Species under a OR/WA BLM Special Status Plant Policy. It is considered threatened or endangered in Oregon but more stable elsewhere (List 2) by the Oregon Natural Heritage Program (1998), and has a State rank of S2 from The Nature Conservancy, which is a species that is imperiled because of rarity or because it is vulnerable to extinction or extirpation with typically 6 to 20 occurrences (Oregon Natural Heritage Program 1998). It is also a candidate for listing as threatened or endangered in Oregon (Oregon Natural Heritage Program 1998). In Washington, Botrychium minganense was previously listed as sensitive but has recently been moved to the Monitor List 3, which are those taxa more abundant and/or less threatened in Washington than previously thought (Washington Natural Heritage Program 1994).

B. Unique Characteristics, Biology, and Ecology

The above-ground or visible parts of Botrychium minganense consist of a single upright stem arising from the ground and terminating in a cluster of tiny ball-like structures, which resemble a bunch of grapes; hence, the often used common name for the genus of "grape-fern". These globular structures (the sporangia) contain the spores necessary for sexual reproduction. Branching off from the main stem is the sterile, fern-like leaf blade (the trophophore). In Botrychium, the portion of the stem below this juncture of the sterile blade with the main stem is referred to as the common stalk, and the portion with the sporangia is called the fertile stalk (sporophore). At the base of the common stalk but just below the ground, Botrychium has several layers of leaf primordia, which are the preformed buds of plants that will emerge in future years.

Botrychium minganense is a small, herbaceous, perennial fern. The sterile blade (trophophore) is dull green in color, narrowly oblong to linear in overall outline, about 10 cm long x 2.5 cm wide. The sterile blade is once-pinnate, with up to 10 pairs of pinnae (segments). In general the segments are well developed, cuneate to flabellate in shape, and spaced separately from each other along the rachis. The margins of the segments are entire to shallowly crenate. The lowest segments are narrowly fan-shaped. The description uses many qualifying adjectives because Botrychium is notorious for morphological variation.

Botrychium minganense can be confused with Botrychium spathulatum but the latter species has a more leathery textured, deltate-shaped sterile blade, and is not suspected to occur within the range of the northern spotted owl. In eastern Washington, Botrychium minganense is often difficult to distinguish from Botrychium crenulatum because of wide variations in leaf morphology, but the latter species is more yellow-green in color and the veins are more pronounced on the leaf segments. Within the range of the northern spotted owl, Botrychium minganense may often be confused with Botrychium lunaria. The main difference is that the leaf segments in B. lunaria are much more broadly fan-shaped and the pairs are arranged closely enough to overlap.

Botrychiums are terrestrial ferns that reproduce by means of microscopic spores (Lellinger 1985). The growth rate is so slow that ordinarily only a single leaf is produced per year -primordia for several years are contained within the bud, and only one primordium matures each season. In Botrychium minganense, asexual reproduction is sometimes accomplished via gemmae, which are spherical units that are produced on the underground stem and are capable of developing into sporophytes (Farrar and Johnson-Groh 1990).

Botrychiums are thought to depend on mycorrhizal relationships with other species in order to thrive. Underground associations between the fern roots and fungi are apparently fragile but essential, and presumably are established during the gametophyte phase (Zika 1992). It may be the fungal symbiont that is most affected by changes in canopy coverage, summer temperature, and soil moisture (Zika 1992). It has been suggested that spore ingestion by animals may be important as a dispersal mechanism based on observations of deer gazing on many Botrychium species.

C. Specific Habitat Associations

Many populations in Oregon and east of the Washington Cascades seem to fit the description summarized by Zika (1992) in a report for Mt. Hood National Forest. The colonies are associated with riparian zones and old-growth western redcedar (Thuja plicata) in dense shade, sparse understory, an alluvium substrate and often a duff layer of Thuja branchlets. On the Wenatchee National Forest most records are from old-growth stands in river bottoms in the western hemlock/devil's club plant association or the western hemlock/wild ginger association (Potash 1998). Soils on the Wenatchee sites are often saturated in the spring (in some instances individuals emerge under running snowmelt), but tend to dry out later in the growing season. Plants do not occur in soils wet enough to support skunkcabbage, but grow adjacent to these areas.

However, within the range of the northern spotted owl there seems to be wide variation in the habitat preference of Botrychium minganense based on the most recent sighting reports. None of the sites on the Gifford Pinchot or Mt. Baker-Snoqualmie National Forests were in old-growth forest. Instead, sites were located in subalpine meadows, mossy talus slopes under bigleaf maple, road cuts, shrub lands, and alder thickets. Most recent sightings on the Wenatchee National Forest are also in nonforested habitats. These populations occur in lush herbaceous meadows (Potash 1998).

D. Range of Botrychium minganense

1. Known Range

Botrychium minganense is a North American species that is wide ranging across Canada from coast to coast. In the United States, the Flora of North America (Morin 1993) shows it occurring in Alaska, Washington, Oregon, Idaho, Montana, Utah, California, Nevada, Wyoming, Arizona, Colorado, North Dakota, Minnesota, Wisconsin, Michigan, New Hampshire, New York, Vermont, and Maine. On federally owned lands within the range of the northern spotted owl, it occurs on USDA Forest Service lands on the Mt. Hood, Willamette, Gifford Pinchot, Mt. Baker-Snoqualmie, Wenatchee, and Okanogan National Forests, and on the Eugene District of BLM. There are no documented sightings of Botrychium minganense within the range of the northern spotted owl in California (Skinner and Pavlik 1994; California Natural Diversity Database 1998).

2. Suspected Range

Sites of Botrychium minganense could be located on federal land in southern Oregon and in the high cascades of northern California (Jepson 1993). There are currently 2 known sites of Botrychium minganense outside the range of the northern spotted owl in California in Fresno and Tehama counties (Skinner and Pavlik 1994; California Natural Diversity Database 1998).

E. Timing of Surveys

Surveys should be conducted May through September when the above ground sporophyte of Botrychium minganense is likely to be present.

F. Threats

Management Recommendations (Potash 1998) identified the major threats to B. minganense as follows:

• Habitat degradation of native plant communities resulting from exotic weed invasion
• Trampling by recreational users or livestock
• Soil compaction
• Botrychium minganense may respond poorly to fire; however, the reaction is unknown at the current time.
• Livestock grazing may have several adverse impacts including direct consumption, trampling, soil compaction, and introduction of exotic weeds
• Burial by surface deposition resulting from erosion after during construction, flooding, or other events.
• Timber harvest may pose indirect impacts in those portions of the range where Botrychium minganense appears to be closely associated with old-growth

REFERENCES

California Natural Diversity Database. 1998. Special Plants List. California Department of Fish and Game. Sacramento, CA.

Farrar, D. R., and C. L. Johnson-Groh. 1990. Subterranean sporophytic gemmae in moonwort ferns, Botrychium subgenus Botrychium. American Journal of Botany 77: 1168-1175.

Hickman, J. (Ed.). 1993. The Jepson manual: Higher plants of California. University of California Press, Berkeley, California.

Lellinger, David B. 1985. A field manual of the ferns and fern-allies of the United States and Canada. Smithsonian Institution Press. Washington, D.C.

Morin, N. (Ed.). 1993. Flora of North America North of Mexico. Volume 2, Pteridophytes and Gymnosperms. Oxford University Press, New York.

Oregon Natural Heritage Program. 1998. Rare, Threatened and Endangered Species of Oregon. Oregon Natural Heritage Program, Portland, Oregon. 92 pp.

Potash, L. 1998. Management Recommendations for Mingan moonwort (Botrychium minganense Victorin), Version 2.0. Unpublished manuscript.

Skinner, M. And B. Pavlik, Eds. 1994. Inventory of rare and endangered vascular plants of California, fifth edition (special publication #1). California Native Plant Society. Sacramento, CA.

USDA Forest Service. 1991. Regional Forester's Sensitive Species List, for Region 6 (Pacific Northwest).

USDA Forest Service and USDI Bureau of Land Management. 1994. Final supplemental environmental impact statement on managing of habitat for late successional and old-growth species within the range of the northern spotted owl. Portland, Oregon.

Washington Natural Heritage Program. 1994. Endangered, threatened, and sensitive vascular plants of Washington. Department of Natural Resources. Olympia. 52p.

Zika, Peter F. 1992. Draft management guide for rare Botrychium species (moonworts and grapeferns) for the Mt. Hood National Forest. Oregon Natural Heritage Program unpublished report for the USDA Forest Service, Portland.