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BC Conservation Data Centre: Species Summary


Botrychium hesperium
western moonwort

 
Scientific Name: Botrychium hesperium (Maxon & Clausen) W.H. Wagner & Lellinger
English Name: western moonwort
 
Classification / Taxonomy
Scientific Name - Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Classification Level: Species
Species Group: Vascular Plant
Species Code: BOTRHES
Kingdom Phylum Class Order Family
Plantae Filicinophyta Ophioglossopsida Ophioglossales Ophioglossaceae
   
Conservation Status / Legal Designation
Global Status: G4 (Jan 2018)
Provincial Status: S4 (Apr 2019)
BC List: Yellow
Provincial FRPA list:   
Provincial Wildlife Act:
COSEWIC Status:
SARA Schedule:
General Status Canada: 3 - Sensitive (2010)
   
Ecology & Life History
General Description: Western Moonwort is a small perennial fern with a single erect frond, 3-13 cm high. It is divided into a sterile segment and a fertile segment. The sterile segment has a stalk 0-4 mm long, and a broadly lance-shaped to triangular blade that is pinnately divided with 1-6 pairs of closely adjacent leaflets (pinnae). The basal pinnae are usually partly to wholly pinnately divided and are larger than the lobed or entire-margined upper pinnae. The fertile segment is 2-3 times as long as the sterile segment and 1-3 times pinnately divided into linear segments that bear the spores.
Technical Description:
Diagnostic Characteristics: Botrychium subgenus Botrychium is a large group of very similar species, many of which have been recently described. A technical manual should be consulted for positive identification. The deeply pinnately lobed basal pinnae help separate this species from most others in its range. Farrar (2005) provides the following characteristics differentiating B. "michganense" from B. hesperium: B. "michiganense" differs in its usually unstalked to short-stalked (< 2mm) trophophore and its abrupt transition from the elongated and deeply dissected basal pinnae to the distinctly smaller and scarcely dissected second pinnae pair. Where the two species co-occur (northern Rocky Mountains), B. hesperium var. fenestratum further differs from B. "michiganense" in having pinnae and pinnules overlapping or nearly so. The typical variety of B. hesperium in the southern Rocky Mountains has little to no dissection in pinnae above the first pair and only shallow and narrow dissection in its basal pinnae; however, the typical variety of B. hesperium seldom co-occurs with B. "michiganense".
Similar Species:
Habitats:
(Type / Subtype / Dependence) 		Agriculture / Pasture/Old Field / Facultative - occasional use
Grassland/Shrub / Grassland / Facultative - frequent use
Grassland/Shrub / Meadow / Obligate
Global Habitat Comments: Occurs in the forested montane zone, where the forest is relatively open-canopied and/or within open habitat types, which tend to be subject to periodic disturbance and include subalpine meadows, snow fields, mesic grassy slopes, prairie pothole meadows, edges of lakes, gravel bars, and roadsides. Soils are dry to moist and tend to be coarse and gravelly. Common moonwort associates include B. paradoxum, B. lunaria and B. lanceolatum. Anderson and Cariveau (2004) note that apparently suitable habitat is plentiful within the range but is often not occupied by this species; they hypothesize that this may be due to limitations in successful migration to the site, or the result of other unknown ecological parameters, such as insufficient time since a disturbance event and/or lack of appropriate mycorrhizal symbionts. 1000 - 3500 m.
Provincial Phenology:
(1st half of month/
2nd half of month)
Elevation (m) (min / max): Provincial: 
Known Pests:
Pollen Vector:
Pollinator:
Dispersal:
   
 
Provincial Inventory
Inventory Priority:
Ownership of occurrences (Known locations):
Inventory Need:
 
Economic Attributes
 
Distribution
Endemic: N
Global Range Comment: Botrychium hesperium ranges from Yukon south through the Rocky Mountains to northern Arizona (Farrar 2011; Gilman et al. 2015). It may also occur in Alaska (Farrar 2011), Saskatchewan (VASCAN 2018), and New Mexico (BONAP 2014). Reports from Michigan, Ontario, and Minnesota, are now identified as Botrychium michiganense (Gilman et al. 2015). Botrychium hesperium may be confused with similar species, especially B. michiganense (in the north) and B. echo (in the south) (Farrar 2011).
Disjunct, more common elsewhere:
Peripheral, major distribution elsewhere:
 
Authors / Contributors
Global Information Author: JM
Last Updated: Oct 06, 1994
Provincial Information Author:
Last Updated:
Last Literature Search:
   
References and Related Literature
Ahlenslager, K. and P. Lesica. 1995. Observations of BOTRYCHIUM WATERTONENSE and its putative parent species, B. HESPERIUM and B. PARADOXUM. Draft manuscript prepared in cooperation with Waterton Lakes National Park, USFWS, and Montana Natural Heritage Program. 13 pp.
Douglas, G.W., D. Meidinger, and J. Penny. 2002. Rare Native Vascular Plants of British Columbia, 2nd ed. B.C. Conserv. Data Centre, Terrestrial Inf. Branch, Victoria. 358pp.
Douglas, G.W., D. Meidinger, and J. Pojar, editors. 2000. The Illustrated Flora of British Columbia. Volume 5. Dicotyledons (Salicaceae through Zygophyllaceae) and Pteridophytes. British Columbia Ministry of Environment, Lands and Parks and British Columbia Ministry of Forests, Victoria.
Douglas, G.W., D. Meidinger, and J. Pojar, eds. 2000. Illustrated Flora of British Columbia, Vol. 5, Dicotyledons (Salicaceae through Zygophyllaceae) and Pteridophytes. B.C. Minist. Environ., Lands and Parks, and B.C. Minist. For., Victoria. 389pp.
Farrar, D. R. 2005b, January last update. Botrychium hesperium species description, map, and photo page. In Farrar, D.R. 2006, June last update. Systematics of moonworts Botrychium subgenus Botrychium. Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames. Online. Available: http://www.public.iastate.edu/~herbarium/botrychium.html (Accessed 2008)
Farrar, D. R. 2005c, January last update. Botrychium michiganense species description, map, and photo page. In Farrar, D.R. 2006, June last update. Systematics of moonworts Botrychium subgenus Botrychium. Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames. Online. Available: http://www.public.iastate.edu/~herbarium/botrychium.html (Accessed 2008)
Flora of North America Editorial Committee (FNA). 1993a. Flora of North America north of Mexico. Vol. 2. Pteridophytes and gymnosperms. Oxford Univ. Press, New York. xvi + 475 pp.
Heidel, Bonnie. Personal Communication. Lead Botanist. Wyoming Natural Diversity Database. University of Wyoming, Laramie, WY
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.
Mantas, M. and R. S. Wirt. 1995. Moonworts of western Montana (BOTRYCHIUM subgenus BOTRYCHIUM). Flathead National Forest. 103 pp.
Montana Natural Heritage Program. Montana Plant Field Guide. Online. Available: http://mtnhp.org/plants/plantguide.asp (Accessed 2006).
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. Jr. and F.S. Wagner. 1986. Three new species of moonworts (Botrychium subg. Botrychium) endemic in western North America. American Fern Journal 76(2):33-47.
Wagner, W.H., Jr., and F. Wagner. 1981. New species of moonworts, Botrychium subg. Botrychium (Ophioglossaceae), from North America. American Fern J. 71(1):20, 26.
 

Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.

Suggested Citation:

B.C. Conservation Data Centre. 1994. Species Summary: Botrychium hesperium. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Apr 25, 2026).