Rare Species Guide

  Synonyms

Botrychium lunaria var. minganense

  Basis for Listing

Botrychium minganense is a widespread moonwort, occurring in North America at northern latitudes and at higher elevations in the south. It occurs from Newfoundland and New England westward across the northern U.S. and Canada to Alaska, and in the western mountains. One occurrence has also been reported from outside North America in Iceland (Farrar 2006).

Minnesota's first documentation of B. minganense was in 1894 from Lake of the Woods County. The species remained very poorly collected in the state until the early 1990's when Herb and Florence Wagner, from the University of Michigan, generated much enthusiasm and widespread interest in Botrychium species. As of 2008, approximately 44 occurrences had been reported in Minnesota. Over half of these are from the Chippewa Plains ecological subsection (Minnesota DNR 2003) located in the north central portion of the state. It is not known however, how many of these populations may still exist today.

Botrychium minganense's rather small size often makes it difficult to locate, and many Botrychium species are also very challenging to accurately identify once found. Furthermore, it is common for multiple species of Botrychium to occur intermixed at the same location. Most Minnesota B. minganense populations are reported to contain only a few plants (1-5) while several populations reportedly have 20-150+ individuals. Botrychium minganense was listed as a special concern species in Minnesota in 1996.

  Description

Botrychium minganense is a small, perennial fern 8-25 cm (3.1-9.8 in.) in height. It is divided above ground into the spore bearing portion (sporophore) and the sterile blade (trophophore). The trophophore is yellowish-green, clearly stalked, and has up to 10 pairs of pinnae. Pinnae are often fan shaped with entire to shallowly lobed margins, and of similar size and spacing along the rachis. The sporophore is typically equal to or longer than the trophophore at the time of spore release.

Botrychium minganense is most readily confused with B. neolunaria (New World moonwort), B. pallidum (pale moonwort), and B. spathulatum (spatulate moonwort). Botrychium identification requires careful examination and often includes final determination from an authority. Botrychium minganense is tetraploid with the probable parentage of B. neolunaria and a species similar to B. pallidum (Farrar 2006).

  Habitat

In Minnesota, B. minganense has most frequently been found in mesic hardwood forests. It has also been observed in upland cedar forest, aspen-fir forest, wet cliff (mossy ledge of waterfalls), and old openings and trails. Associated plant species may include other species of Botrychium (moonworts & grape-ferns), Acer saccharum (sugar maple), Tilia americana (basswood), Uvularia grandiflora (large-flowered bellwort), and Aralia nudicaulis (wild sarsaparilla).

Across its range, habitat conditions vary from sunny to densely shaded and from dry to permanently saturated. Habitats include forests, meadows, fens, and seeps. Botrychium minganense is sometimes found in areas of older (> 10 years) disturbance such as logging roads and road edges (Farrar 2006).

  Biology / Life History

The sexual life cycle of Botrychiums is characterized by an alternation of generations between sporophytes and gametophytes. Botrychiums reproduce by spores shed from the thick walled sporangia of the sporophore. Spores find their way down into the soil and further develop into subterranean gametophytes. Gametophytes contain no chlorophyll and develop mycorrhizal relationships for nourishment. They typically exist underground for a number of years before producing eggs and sperm. Self-fertilization often occurs, where eggs are fertilized from the sperm of the same plant. The fertilized egg further develops as the new sporophyte, taking several years to surface above ground and produce its first frond and spores. Plants are perennial, and may not produce above ground parts every year. Botrychium minganense is also capable of asexual reproduction by the production of tiny gemmae at the root bases (D. Farrar, Iowa State University, pers. comm.). These gemmae have the ability to grow into new plants.

The best time to search for Botrychium minganense is when the plants are fully mature, often between mid-June and mid-August, though plants have been observed from late May to late September. Prime search times may vary as they are influenced by habitat type, precipitation, etc. Plants releasing spores are one sign of mature plants; immature plants may be impossible to accurately identify.

  Conservation / Management

Although we continue to gain a better understanding of species distribution and abundance, we often know little more. The most obvious threats to Botrychium minganense are the loss and degradation of habitat. However, finer details regarding specific habitat requirements are much less certain. More specific threats likely include changes in light, moisture, and mycorrhizae; earthworm invasion; insectivory and herbivory; and competition from non-native species. Well-designed monitoring efforts are necessary in order to better understand species ecology and how populations are responding to management activities and a changing environment. Ample opportunities currently exist across land ownerships to learn more about the biology and ecology of this interesting small fern.

  Conservation Efforts in Minnesota

Botrychium minganense populations occur on tribal, state, federal, and other land ownerships. While many of the populations occur on state and federal land, few if any occur in areas that are formally protected. In 2009, survey work will continue in portions of the Chippewa Plains, Nashwauk Uplands, and Border Lakes subsections, all of which have potential for new discoveries of B. minganense.

  References and Additional Information

Chadde, S., and G. Kudray. 2001. Conservation assessment for Botrychium minganense (Mingan Moonwort). U.S. Forest Service, Eastern Region, Milwaukee, Wisconsin. Accessed 9 April 2009.

Farrar, D. R. 2006. Moonwort (Botrychium) Systematics. . Accessed 13 Apr 2009.

Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp.

Smith, W. R. 2023. Ferns and lycophytes of Minnesota: the complete guide to species identification. University of Minnesota Press, Minneapolis. 368 pp.

Wagner, W. H., Jr., and F. S. Wagner. 1993. Botrychium. Pages 86-101 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 2. Oxford University Press, New York, New York.