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Montana Field Guides

Peculiar Moonwort - Botrychium paradoxum

State Rank Reason (see State Rank above)
This moonwort species is known to occur in western Montana from over two dozen extant occurrences, almost all of which are on federally-managed lands. Many occurrences are small in size and occupy mesic meadows and bunchgrass communities. Potential impacts to the these sites include livestock grazing, weed invasion and recreational uses. Though some threats exist to individual occurrences, the species as a whole is not highly threatened by any single or combination of potential impacts in the state.
  • Details on Status Ranking and Review
    Peculiar Moonwort (Botrychium paradoxum) Conservation Status Review
    Review Date = 10/31/2012
    View State Conservation Rank Criteria
    Population Size

    Score2 - Small: Generally 2,000-10,000 individuals.

    Range Extent

    Score1 - Peripheral, Disjunct or Sporadic Distribution in MT: Widespread species that is peripheral, disjunct or sporadically distributed within MT such that it occurs in <5% of the state (<7,500 sq. miles or the combined area of Beaverhead and Ravalli Counties) or is restricted to 4-5 sub-basins.

    CommentRegional endemic from south central Utah, northward to Montana and Washington and into southern British Columbia, Alberta and Saskatchewan

    Area of Occupancy

    Score1 - Moderate: Generally occurring in 11-25 Subwatersheds (6th Code HUC’s).

    Environmental Specificity

    Score1 - Moderate: Species is restricted to a specific habitat that is more widely distributed or to several restricted habitats and is typically dependent upon relatively unaltered, good-quality habitat (C Values of 5-7).

    Long-term Trend

    CommentTrend data lacking, though probably relatively stable with fluctuating population levels.


    Score0-1 - Stable to Minor Declines:

    CommentTrends are undocumented, though populations are likely stable or experiencing only minor declines.


    Score1 - Medium: 11-30% of the populations are being negatively impacted or are likely to be impacted by one or more activities or agents, which are expected to result in decreased populations and/or habitat quality and/or quantity.

    CommentWeed invasion may negatively impact some populations.

    Intrinsic Vulnerability

    Score1 - Moderate Vulnerability: Specific biological attributes, unusual life history characteristics or limited reproductive potential makes the species susceptible to extirpation from stochastic events or other adverse impacts to its habitat and slow to recover.

    Raw Conservation Status Score

    Score 7 to 8 total points scored out of a possible 19.

General Description
Peculiar moonwort is a small perennial fern with a single above ground frond. The frond varies in height up to about 15 cm tall, is glaucous green, somewhat succulent, and divided into two similar segments which share a common stalk. The segments may be unbranched in small plants or branched in larger plants and are both fertile and bear 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.

Diagnostic Characteristics
Botrychium paradoxum is perhaps the easiest of moonworts to recognize, being the only species to lack a sterile laminar frond segment, but other species could be mistaken for it if the sterile segment has been browsed or bears marginal sporangia. Reliable field determination of moonworts depends on the careful use of technical keys and comparison with silhouette outlines of verified specimens. It is 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.

Species Range
Montana Range Range Descriptions


Range Comments
In MT from Lincoln County east to Sweet Grass County; southern BC to SK (barely) south through WA, ID, MT, WY, CO, and UT, with a disjunct occurrence in east-central CA (Donald Farrar, Iowa State Univesity, unpublished ms.)

Observations in Montana Natural Heritage Program Database
Number of Observations: 64

(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)

Mesic meadows associated with spruce and lodgepole pine forests in the montane and subalpine zones; also found in springy western red cedar forests.
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

Ecological Systems Associated with this Species

  • Additional ReferencesLegend:   View Online Publication
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    • Ahlenslager, K. and P. Lesica. 1996. Observations of Botrychium x watertonense and its putative parent species, B. hesperium and B. paradoxum. American Fern Journal 86(1):1-7.
    • Farrar, Donald. 2011. Moonwort (Botrychium) Systematics. Ada Hayden Herbarium. Iowa State University.
    • Lesica, P. and K. Ahlenslager. 1995. Demography and life history of three sympatric species of Botrychium subg. Botrychium in Waterton Lakes National Park, Alberta, Canada. Draft manuscript prepared in cooperation with Waterton National Park, U.S. Fish and Wildlife Service, and Montana Natural Heritage Program. 22 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.
    • Vanderhorst, J.P. 1993. Survey for Botrychium paradoxum in the vicinity of Storm Lake, Deerlodge National Forest. Unpublished report to the U.S. Fish and Wildlife Service. Montana Natural Heritage Program, Helena. 45 pp.
    • Wagner, D.H. 1992. Guide to the species of Botrychium in Oregon, November 1992. Unpublished report. USDA Forest Service 19 pp., plus figures.
    • Wagner, Jr., W.H., F.S. Wagner, C. Haufler and J.K. Emerson. 1984. A new nothospecies of moonwort (Ophioglossaceae, Botrychium). Canadian Journal of Botany 62:629-634.
    • Wagner, W. H. and F. S. Wagner. 1993. Ophioglossaceae. In: Flora of North America Editorial Committee, eds. 1993. Flora of North America North of Mexico. 3+ vols. New York and Oxford. Vol. 2, pp. 85-106.
    • Wagner, W.H., and F.S Wagner. 1981. New Species of Moonworts, Botrychium Subgenus. Botrychium, From American Fern Journal 71:20-30.
    • Zika, P. F. 1994. A draft management plan for the moonworts Botrychium ascendens, B. crenulatum, B. paradoxum, and B. pedunculosum in the Wallowa-Whitman, Umatilla, and Ochoco National Forests. Unpublished report. Oregon Natural Heritage Program, Portland, OR. 41 pages plus figures, tables and appendices.
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Citation for data on this website:
Peculiar Moonwort — Botrychium paradoxum.  Montana Field Guide.  .  Retrieved on , from