Rare Species Guide

  Basis for Listing

Botrychium campestre var. campestre (prairie moonwort) was first discovered in 1982 and described eight years later (Wagner and Wagner 1990). Until that time, no one knew that Botrychium spp. (moonworts) occurred in prairies. The discovery sparked considerable interest among botanists in finding more sites of this species, and in trying to find out if other undescribed moonworts could be found. Results have been quite impressive; we now know that B. campestre var. campestre ranges across the whole continent. Botanists have also discovered previously undescribed species of Botrychium from prairies and a variety of prairie-like habitats. The actual rarity of B. campestre var. campestre is difficult to judge at this time. There are now numerous records, but they are the result of an unprecedented search effort. Further searches will undoubtedly discover additional sites, and it is possible that at some time in the future B. campestre var. campestre will be thought of as relatively common. Botrychium campestre var. campestre was listed as a special concern species in Minnesota in 1996.

  Description

Botrychium campestre var. campestre is a small, inconspicuous fern that can be very difficult to find. All that is seen above ground is a single leaf divided into a sterile photosynthetic portion and a fertile spore-bearing portion. The shape of the sterile portion is diagnostic for Botrychiums. In B. campestre var. campestre, the sterile portion is sessile, oblong in outline, and longitudinally folded. The maximum size is normally about 4 cm (1.6 in.) in length and 1.3 cm (0.5 in.) in width, and it has a fleshy texture. It is normally divided into 5 pairs of linear or linear-spatulate segments. The margins of each segment are crenate or dentate and are usually notched or cleft into 2 or several secondary segments. Positive identification will likely require the aid of a specialist who has experience with this species. In every case, a leaf specimen will need to be collected, carefully pressed, and dried. Photographs are not adequate.

  Habitat

As its name implies, B. campestre var. campestre is primarily a prairie species. It is found in coarse, well-drained glacial till or in thin loess over bedrock in plant communities that include dry prairies, dry hill prairies, dry bedrock bluff prairies, and sand-gravel prairies. The dominant species are usually clump-forming grasses such as Schizachyrium scoparium var. scoparium (little bluestem), Andropogon gerardii (big bluestem), and Bouteloua curtipendula var. curtipendula (side oats gramma). In nearly all cases, the prairie habitats where B. campestre var. campestre is found are fairly high quality, in ecological terms, and have no history of agriculture. Habitats also tend to be free of non-native sod-forming grasses such as Bromus inermis (smooth brome). In addition to prairies, there are a cluster of B. campestre var. campestre records from the Iron Range in northeastern Minnesota, which is within the forested region of the state. Specifically, the records are from sediment basins used by iron ore and taconite processing plants. When the basins become filled with sediments, they are drained of their water and gradually become colonized by early successional plant species, primarily grasses, forbs, and tree saplings. At this point, the texture of the sediments and the structure of the plant community create an ideal habitat for many species of Botrychium, including B. campestre var. campestre. Exactly how B. campestre var. campestre arrives at these sites and where it comes from remains somewhat of a mystery.

  Biology / Life History

Botrychium campestre var. campestre is a small, terrestrial fern with a complex and poorly understood life history. The single leaf is the only part of the plant that appears above ground, and it is divided into a spore-bearing portion and a photosynthetic portion. The leaf appears in early spring and dies-back in late spring or early summer. In drought years, the leaf may die-back sooner or it may not appear above ground at all. In some cases, this may result in mortality; in other cases the plant survives and sends up a leaf the following year, if moisture conditions have improved (Johnson-Groh 1999). It has been reported that B. campestre var. campestre is mycorrhizal, meaning it receives a portion of its nutrients from soil fungi that inhabit all native prairies. Sexual reproduction is achieved by spores that are dispersed by wind currents, though the spores generally travel no more than a few meters. Asexual reproduction is achieved by gemmae. These are small, spherical vegetative propagules that are produced in dense clusters at the root bases (Farrar and Johnson-Groh 1990). Botrychium campestre var. campestre is one of four moonwort species that commonly produce gemmae.

The best time to search for B. campestre var. campestre is from mid-May to the end of June; by mid-summer the plants will have disappeared.

  Conservation / Management

Prairie habitats need to be maintained in a healthy condition, especially the soil biotic environment. Botrychium campestre var. campestre is known to be susceptible to fire, so prescribed burns should be scheduled for early spring before the plants emerge from the ground. The conservation value of B. campestre var. campestre populations that occur in tailings basins is difficult to determine, but should not be dismissed. Such habitats are presumably in a rapid state of vegetative succession, that is, in transition from an open prairie-like habitat to a closed forest habitat. The transition period may exist for a relatively short period of time, perhaps only 20-40 years. It is not known for sure, but it is hypothesized that when these habitats begin to resemble a forest, the populations of B. campestre var. campestre will disappear. The role of these short-lived populations in the ecology of the species is difficult to determine, but they may serve as a source of spores or vegetative propagules for the colonization of other nearby habitats.

  Conservation Efforts in Minnesota

A number of B. campestre var. campestre habitats occur on public or private lands that are being preserved for their ecological or environmental values. Although there is little supporting documentation, it seems that B. campestre var. campestre is thriving at several of these sites.

  References and Additional Information

Chadde, S., and G. Kudray. 2001. Conservation assessment for Iowa Moonwort (Botrychium campestre). U.S. Forest Service, Eastern Region, Milwaukee, Wisconsin. Accessed 16 September 2009.

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

Farrar, D. R., and C. L. Johnson Groh. 1990. Subterranean sporophytic gemmae in moonwort ferns, Botrychium subgenus Botrychium. American Journal of Botany 77(9):1168-1175.

Johnson-Groh, C. L. 1999. Population biology of Botrychium (moonworts): Status report on Minnesota Botrychium. Permanent plot monitoring. Unpublished report to the Minnesota Department of Natural Resources.

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. 1990b. Moonworts (Botrychium subg. Botrychium) of the Upper Great Lakes region, U.S.A. and Canada, with descriptions of two new species. Contributions from the University of Michigan Herbarium 17:313-325.

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.