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Montana Field Guides

Mingan Island Moonwort - Botrychium minganense

Native Species

Global Rank: G5
State Rank: S4
(see State Rank Reason below)

Agency Status


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State Rank Reason (see State Rank above)
Documented from over 90 occurrences in Montana. These are scattered across western and central Montana with the largest concentration occurring in the northwest corner of the state. Population numbers are usually small at each site, numbering in the 10's to occassionally the 100's. A thorough review of the population demographics and risks to the species' viability are needed to document its current state rank.
General Description
Mingan Island Moonwort is a small perennial fern with a single aboveground frond. The frond varies in height, but may reach about 20 cm. It is divided into two segments which share a common stalk, and it is usually a deep, dull green and somewhat fleshy. The sterile segment is once pinnatifid with up to 10 usually well separated pairs of pinnae. The pinnae are variable; they are generally narrowly fan-shaped with rounded, entire margined apices, but can be broader and may be lobed or have incised margins. The fertile segment is longer than the sterile segment, is branched, and bears grape-like sporangia. Spores germinate underground and develop into minute subterranean, non-photosynthetic gametophytes which depend on an endophytic fungus for nourishment.

Fronds mature in July-August.

Diagnostic Characteristics
Botrychium minganense is highly variable, but the dull green color, somewhat fleshy texture, and the many well-divided, relatively narrow, entire-margined pinnae are typical of Montana plants. This species is most easily confused with B. ascendens, B. crenulatum and B. lunaria; small plants may also resemble B. montanum and B. simplex. Reliable field determination of moonworts depends on the careful use of technical keys and comparison with silhouette outlines of verified specimens. Identification can be complicated because there is often a high degree of morphological variability between individuals in a population and between populations of the same species; several species may grow together at the same site, and the few diagnostic characters may not be apparent in small plants.

Mingan Island Moonwort - Botrychium minganense
*Plants: Green when fresh.
*Pinnae: Entire to symmetrically 3- to 5- lobed; lobes are shallow. Stalk of the lower pinnae are one-quarter the width of the rachis.
*Sporophore: Branches are definitively stalked. Sporangia do not obscure the sporophore's rachis.

Wishbone Moonwort - Botrychium furculatum, SOC
*Plants: Lighter colored when fresh. Plants can be glaucous (seldom blue-green glaucous). Plants typically are yellow- to white-green.
*Pinnae: Irregularly toothed or crenate, often asymmetrical. Stalks do not appear narrow.
*Sporophore: Lower branches are usually short-stalked to sessile. Sporangia partially obscures the rachis.

Species Range
Montana Range Range Descriptions


Range Comments
One of the most widespread moonworts in North America, occurring in practially all parts of Canada and Alaska and throughout the western United States, south to Arizona and New Mexico and in all the US/Canadian border states.

Observations in Montana Natural Heritage Program Database
Number of Observations: 300

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

A broad variety of habitats including grasslands, old growth and second growth deciduous and coniferous forests, and riparian zones. In northwest MT it is usually found at hydrological microfeatures, such as seepy draws, benches, stream bottoms, and wetland edges in maturing to old growth stands of western red cedar.

  • Additional ReferencesLegend:   View Online Publication
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    • Achuff, P.L. 1992. Status review of Botrychium minganense USDA Forest Service Region 1 Lolo National Forest. Montana Natural Heritage Program, Helena, MT. 26 pp.
    • Caicco, S. L. 1987. Field investigations of selected sensitive plant species on the Idaho Panhandle National Forest. Idaho Natural Heritage Program, Idaho Department of Fish and Game, Boise, Idaho. 44 pp.
    • Farrar, Donald. 2011. Moonwort (Botrychium) Systematics. Ada Hayden Herbarium. Iowa State University.
    • Lesica, P. and K. Ahlenslager. 1994. Demographic monitoring of three species of Botrychium (Ophioglossaceae) in Waterton Lakes Park, Alberta: 1993 progress report. Unpublished report to the U.S. Fish and Wildlife Service. Montana Natural Heritage Program, Helena, Montana. 19 pp.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
    • Mantas, M. and R.S. Wirt. 1995. Moonworts of western Montana (Botrychium subgenus Botrychium). Flathead National Forest. 103 pp.
    • Popovich, S.J. and D.R. Farrar. 2020. Botrychium furculatum (Ophioglossaceae), a New Moonwort Species from the Rocky Mountains of North America. American Fern Journal 110(4):165–182.
    • Vanderhorst, J.P. 1997. Conservation assessment of sensitive moonworts (Botrychium subgenus Botrychium) on the Kootenai National Forest. Unpublished report. Montana Natural Heritage Program, Helena, MT 82 pp. plus appendices.
    • Wagner, D.H. 1992. Guide to the species of Botrychium in Oregon, November 1992. Unpublished report. USDA Forest Service 19 pp., plus figures.
    • Wagner, W. and F. Wagner. 1986. Three New Species of Moonworts (Botrychium Subgenus Botrychium) Endemic in Western North America. American Fern Journal 76 (2):3347
    • Wagner, W. H., Jr. and F. S. Wagner. 1990. Notes on the fan-leaflet group of moonworts in North America with descriptions of two new members. American Fern Journal 80:73-81.
    • Wagner, W. H., Jr., and F. S. Wagner. 1990. Moonworts (Botrychium subg. Botrychium) of the upper Great Lakes Region, U.S.A. and Canada, with descriptions of two new species. Contributions of the University of Michigan Herbarium 17: 313-325.
    • Wagner, W.H., and E.S. Wagner. 1983. Genus communities as a systematic tool in the study of new world Botrychium (Ophioglossaceae). Taxon 32(1): 51-63.
    • Wagner, W.H., Jr. and P.L. Lord. 1956. The morphological and cytological distinctness of Botrychium minganense and B. lunaria in Michigan. Bulletin of the Torrey Botanical Club 83(4): 261-280.
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Citation for data on this website:
Mingan Island Moonwort — Botrychium minganense.  Montana Field Guide.  .  Retrieved on , from