Botrychium pallidum

W.H. Wagner

Pale Moonwort

G4Apparently Secure Found in 1 roadless area NatureServe Explorer →
G4Apparently SecureGlobal Rank
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.154737
Element CodePPOPH01130
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumFilicinophyta
ClassOphioglossopsida
OrderOphioglossales
FamilyOphioglossaceae
GenusBotrychium
Other Common Names
Botryche pâle (FR)
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.
Taxonomic Comments
First described in 1990, from plants formerly identified as B. minganense.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2024-07-29
Change Date2024-07-29
Edition Date2024-07-29
Edition AuthorsK. Crowley, MRO, rev. Spackman, S. and D. Anderson (2000), rev. L. Morse (2001), rev. K. Gravuer (2008), rev. Johnson, J. (2024)
Threat ImpactUnknown
Range Extent>2,500,000 square km (greater than 1,000,000 square miles)
Number of Occurrences81 to >300
Rank Reasons
Botrychium pallidum is a small, inconspicuous fern that has a broad but disjunct range including eastern Maine and eastern Quebec, the Great Lakes region, the Black Hills, the Rocky Mountains, northwestern Montana, southern Alberta, and Saskatchewan. More than 200 occurrences have been documented, but many contain small numbers of aboveground plants. Additional occurrences are expected to be found with continued inventory; the species' range may be more continuous than our present knowledge indicates. The primary threat appears to be the successional overgrowth of habitat; habitat encroachment due to development, agriculture, and recreation is also a concern.
Range Extent Comments
The range of Botrychium pallidum is broad but highly disjunct across North America. It occurs in Saskatchewan, southern Alberta, southeastern British Columbia, and northwestern Montana, central Colorado, the Black Hills of South Dakota, the Great Lakes Region from Minnesota to Ontario and Michigan, the St. Lawrence Seaway of Quebec, and coastal Maine (GBIF 2024, NatureServe 2024). Range extent was estimated using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1993 and 2024 (GBIF 2024, iNaturalist 2024, NatureServe 2024, SEINet 2024).
Occurrences Comments
By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1993 and 2024, it is estimated that there are more than 200 occurrences rangewide (GBIF 2024, iNaturalist 2024, NatureServe 2024, SEINet 2024).
Threat Impact Comments
The primary threat to B. pallidum appears to be loss of its open, grassy habitat to successional overgrowth, which is likely exacerbated by fire suppression. This species' preference for disturbed, open habitat may lead population viability to be dependent on a shifting mosaic of suitable sites opening for colonization, as occupied sites become overgrown and their generally small populations become vulnerable to local extinction (Chadde and Kudray 2001). Habitat encroachment due to development, agriculture, and recreation are also threats to B. pallidum and its habitat (USDA Forest Service 2000 cited in Chadde and Kudray 2001, Williston 2002). In Quebec, the species is locally threatened by riverine erosion in addition to canopy closure (J. Labrecque pers. comm. 2008). Prolonged drought can be a threat in some areas, as water relations are important to moonworts and their supporting mycorrhizae; moonworts are known not to appear above ground in hot dry years (Chadde and Kudray 2001, Johnston 2002). It is also possible though somewhat unlikely that exotic earthworms are a threat to B. pallidum; this threat is known to impact only B. mormo thus far, which occurs in the habitats most likely to be affected (i.e. those with a thick organic surface layer, in contrast to the open, disturbed habitats apparently preferred by B. pallidum) Chadde and Kudray 2001).
Ecology & Habitat

Description

A small perennial fern with a single aboveground frond less than 15 cm tall, with a waxy, pale whitish green color, and divided into two segments that share a common stalk. The sterile segment is once pinnatifid and has up to 5 pairs of fan-shaped pinnae, 2-3 mm long, with concave sides. Each of the pinnae tends to form two lobes, the upper one cleft and larger than the lower. The sterile segment is shaped like a trough along the central axis. The fertile segment is longer than the sterile segment, branched, and bears grape-like sporangia. Leaves appear in late spring to early summer. Spores germinate underground and develop into subterranean gametophytes.

Diagnostic Characteristics

Most easily confused with B. minganense, especially small, sun-grown B. minganense plants. Can be distinguished from B. minganense by (1) its pale green to silvery gray-green or whitish color (although this character may not persist in collected plants), (2) its smaller size, including pinnae only 2-3 mm long compared to the 4-6 mm in B. minganense, (3) its pinna sides concave throughout and most strongly so near their juncture with the outer margin, giving the pinna a mushroom shape, compared to of B. minganense pinnae which are concave near the rachis but are more or less straight along the pinna blade, (4) its folded trophophore blade compared to the flat trophophore blade of B. minganense, and (5) its often unevenly divided outer pinna margins and basal sporophore branches, with the upper lobe longer and broader than the lower lobe; outer pinna margins of B. minganense are entire, or if lobed, symmetrically so, and the basal branches of the sporophore are symmetrically branched. Can be distinguished from B. gallicomontanum by its longer trophophore and sporophore stalks; in B. gallicomontanum, the sporophore stalk is typically less than half the length of the trophophore. Also, the pinnae lobes of B. gallicomontanum are more spreading and linear than those of B. pallidum. Can be distinguished from B. ascendens by its distinctive pinnae folding and outer margins as well; pinna of B. ascendens are wedge-shaped with little curvature in the side margins and outer margins are dentate or cleft symmetrically into spreading lobes. Spores of B. pallidum are much smaller than those of B. minganense, B. gallicomontanum, or B. ascendens. B. pallidum is also one of only four moonwort species that commonly produce dense clusters of minute, spheric gemmae at the root bases (Flora of North America 1993, Chadde and Kudray 2001, Farrar 2005).

Habitat

Botrychium pallidum is most often found in open habitats of sparse to dense herbaceous vegetation, such as grasslands, open meadows and fields. sand dunes, sand hills, sandy ridges, oak barrens, open exposed hillsides, and clifftops. It is occasionally found in the partial shade of open-canopy forests (or in disturbed sites of more closed-canopy forests), including mixed hardwood forest, maple/basswood forest, subalpine fir-Engelmann spruce forest, and red and jack pine communities. Many areas where this plant is found have been affected by disturbance; sites which are kept open due to regular disturbance regimes (e.g. fire, cattle grazing, persistent native ungulate browsing) appear particularly suitable. Other disturbed habitats where this plant has been found include burned or cleared areas, roadsides, grassy ditches, old logging landings and roads, vacant lots, old mining sites, and old fields. It is also occasionally known from wetlands, including ephemeral ponds, streamside areas, and high-elevation subalpine forest wetlands.
Terrestrial Habitats
Forest/WoodlandForest - HardwoodForest - ConiferForest EdgeWoodland - ConiferGrassland/herbaceousOld fieldSand/dune
Palustrine Habitats
TEMPORARY POOLRiparian
Other Nations (2)
United StatesN4
ProvinceRankNative
MaineS1Yes
MinnesotaS3Yes
MichiganS3Yes
WyomingS1Yes
MontanaSNRYes
South DakotaS2Yes
WisconsinS1Yes
CanadaN2
ProvinceRankNative
ManitobaSHYes
SaskatchewanS1Yes
AlbertaS2Yes
OntarioS1Yes
QuebecS1Yes
British ColumbiaS2Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentUnknownUnknownUnknown
2 - Agriculture & aquacultureUnknownUnknownUnknown
2.1 - Annual & perennial non-timber cropsUnknownUnknownUnknown
6 - Human intrusions & disturbanceUnknownUnknownUnknown
6.1 - Recreational activitiesUnknownUnknownUnknown
7 - Natural system modificationsLarge (31-70%)UnknownModerate (short-term)
7.1 - Fire & fire suppressionLarge (31-70%)UnknownModerate (short-term)
7.1.2 - Suppression in fire frequency/intensityLarge (31-70%)UnknownModerate (short-term)
8 - Invasive & other problematic species, genes & diseasesUnknownUnknownUnknown
11 - Climate change & severe weatherPervasive (71-100%)UnknownModerate (short-term)
11.2 - DroughtsPervasive (71-100%)UnknownModerate (short-term)

Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)No
Roadless Areas (1)
North Dakota (1)
AreaForestAcres
Bullion ButteDakota Prairie Grasslands19,877
References (19)
  1. Chadde, S. and G. Kudray. 2001. Conservation assessment for pale moonwort (<i>Botrychium pallidum</i>). Prepared for USDA Forest Service, Region 9 (Eastern Region). Requisition no. 43-54A7-0-0036. Project no. Ottawa-00-06. Online. Available: http://www.fs.fed.us/r9/wildlife/tes/ca-overview/docs/Pale-Moonwort.pdf (Accessed 2008).
  2. Farrar, D. R. 2005d, January last update. <i>Botrychium pallidum</i> species description, map, and photo page. In Farrar, D.R. 2006, June last update. Systematics of moonworts <i>Botrychium </i>subgenus <i>Botrychium</i>. Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames. Online. Available: http://www.public.iastate.edu/~herbarium/botrychium.html (Accessed 2008)
  3. Farrar, Dr. Donald. Dept. of Botany, Iowa State University, Ames, IA. Pers. comm. of April 27, 1995, with Kathy Crowley, MRO.
  4. 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.
  5. Flora of North America Editorial Committee (FNA). 1993b. Flora of North America north of Mexico. Vol. 1. Introduction. Oxford Univ. Press, New York. xxi + 372 pp.
  6. Gilman, A.V. 2004. <i>Botrychium pallidum</i> newly discovered in Maine. American Fern Journal 94(3): 155-162.
  7. Global Biodiversity Information Facility (GBIF). 2024. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2024).
  8. iNaturalist. 2024. Online. Available: https://www.inaturalist.org (accessed 2024).
  9. Johnston, B. C. 2002, 30 September last update. Species Evaluation: <i>Botrychium pallidum</i>. U.S. Forest Service Rocky Mountain Region (Region 2) Species Conservation Program: Species Evaluations and Rationales. Online. Available: http://www.fs.fed.us/r2/projects/scp/evalrationale/evaluations/ferns/botrychiumpallidum.pdf (Accessed 2008).
  10. 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.
  11. Kemper, Todd. Personal communication. Senior Botanist, Alberta Natural Heritage Information Centre, Alberta Community Development, Parks and Protected Areas Division, Edmonton, AB.
  12. Labrecque, Jacques. Personal communication. Botaniste, Ministère du Développement durable, de l'Environnement et des Parcs. Direction du patrimoine écologique et des parcs. Québec, Québec, Canada.
  13. Montana Natural Heritage Program. Montana Plant Field Guide. Online. Available: http://mtnhp.org/plants/plantguide.asp (Accessed 2006).
  14. NatureServe. 2024. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  15. Oldham, Michael. Personal communication. Botanist, Ontario Natural Heritage Information Centre.
  16. Southwest Environmental Information Network (SEINet). 2024. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2024).
  17. Wagner, W.H., and E.S. Wagner. 1983. Genus communities as a systematic tool in the study of new world <i>Botrychium </i>(Ophioglossaceae). Taxon 32(1): 51-63.
  18. Wagner, W.H., Jr. and F.S. Wagner. 1990. Notes on the fan-leaflet group of moonworts in North America with descriptions of two new members. American Fern Journal 80(3):73-81.
  19. Williston, P. 2002. The Botrychiaceae of Alberta: A survey of element occurrences of the genera <i>Botrychium</i> and <i>Sceptridium</i> in Alberta. A report by Patrick Williston, Mnium Ecological Research, to Resource Data Division, Alberta Sustainable Resource Development. January 2002. Online. Available: http://www.tprc.alberta.ca/parks/heritageinfocentre/docs/botrychium_report_final%202002.pdf (Accessed 2008).