- Scientific name: Botrychium simplex E. Hitchc.
- Species of Greatest Conservation Need (MA State Wildlife Action Plan)
Description
Least moonwort is a diminutive, perennial, fern species with a short rhizome, producing one sterile and fertile frond per season. The sterile and fertile fronds typically diverge near the ground surface (0-3 cm [1.2 in]), though they may diverge up to midway along the total height of the plant. The fronds are mostly 3-15 cm (1.2-5.9 in) in height with a simple (or once or twice pinnate) fertile blade, 0.3-5 cm (0.12-2 in) in length. This fertile blade is one to four times as long as the sterile blade. Spores are finely reticulate. The sterile blade may be simple or be once or twice divided. Due to its low stature, it may be overlooked and thus under-reported. The sterile blade color ranges from dull to bright green or whitish-green.
Distribution and abundance
Least moonwort is known from much of the northern US and across Canada; however, in most of its range (where it has been evaluated), it is considered vulnerable, imperiled, or critically imperiled.It is thought to be extirpated from Connecticut, Illinois, Maryland, and Ohio (NatureServe 2025). In Massachusetts, it is considered critically imperiled, and although MassWildlife’s Natural Heritage Endangered Species Program (NHESP) database has historic records of this species from Essex, Hampshire, Hampden and Franklin counties, the two current populations are known from Berkshire County. It is also known from Europe. Plants may be dormant for one to several years at a time, making the abundance in any one population difficult to assess.
Habitat
The habitats that support least moonwort include open wet meadows, roadside ditches, and edges of pastures. Soil types are slightly acidic to circumneutral. It appears that this species needs early to mid-successional sites. Associated species may include sanicles, long-spurred violet, bulblet fern, fragile fern, sugar maple, white ash, witch hazel, white pine, and eastern hemlock.
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Threats
Threats to the persistence of least moonwort may include alteration of its habitat through development, road maintenance, timber harvest, and recreation. Changes in hydrology will impact this species, including water use and diversions which may lead to habitat loss and change (NatureServe 2025). Effects of small population size, encroachment of woody plants and invasive species, global climate change, and pollution are also probably contributing factors to its apparent decline. Propagation of least moonwort has had minimal success, perhaps in part because this species relies heavily on its interaction with mycorrhizal fungus.
References
Anderson, D.G. (2006, May 22). Botrychium simplex E. Hitchcock (little grapefern): a technical conservation assessment. [Online]. USDA Forest Service, Rocky Mountain Region. Available: http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/ste lprdb5206970.pdf [August 18, 2015].
Gleason, H.A., and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada, Second Edition. The New York Botanical Garden, Bronx, New York.
Haines, A. 2011. Flora Novae Angliae. The New England Wild Flower Society. Yale University Press, New Haven, CT.
NatureServe. 2025. NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org/. Accessed: 5/19/2025.
Contact
| Date published: | April 8, 2025 |
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