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Pediomelum castoreum

(S. Wats.) Rydb.

Beaver Scurfpea

G3Vulnerable Found in 1 roadless area NatureServe Explorer →
G3VulnerableGlobal Rank
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.158306
Element CodePDFAB5L050
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single nation
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderFabales
FamilyFabaceae
GenusPediomelum
Synonyms
Psoralea castoreaS. Watson
Other Common Names
beaver Indian breadroot (EN) Beaver Indian-breadroot (EN)
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.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-03-05
Change Date1994-04-25
Edition Date1989-01-18
Edition AuthorsRusso, Mary (TNC WRO, 1989?), rev. D. Gries (1999?), rev. Soteropoulos (2025)
Threat ImpactUnknown
Range Extent20,000-200,000 square km (about 8000-80,000 square miles)
Number of Occurrences21 - 80
Rank Reasons
Pediomelum castoreum is a perennial herb in open desert scrub occurring in the southwestern United States in northwestern Arizona, southern Nevada, and southeastern California. There are an estimated 62 occurrences that face threats from development, road maintenance, cattle ranches, and recreational activities, though the species appears to prefer light disturbance. Long-term trends in the number of occurrences suggests a decline of approximately 35%, though field surveys of potentially historic occurrences are needed to determine if plants are extant. Monitoring of populations should be conducted to improve our understanding of reproduction, plant abundance, threats, and trends, as well as continuing conservation measures to protect the taxon.
Range Extent Comments
Pediomelum castoreum occurs in the southwestern United States in northwestern Arizona (Mohave County), southern Nevada (Clark and Lincoln counties), and southeastern California (Inyo and San Bernadino counties) (FNA 2023). Range extent was estimated to be approximately 49,000 square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025 (RARECAT 2024, GBIF 2025, iNaturalist 2025, NatureServe 2025, SEINet 2025).
Occurrences Comments
By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025, it is estimated that there are 62 occurrences rangewide (RARECAT 2024, GBIF 2025, iNaturalist 2025, NatureServe 2025, SEINet 2025).
Threat Impact Comments
Although threats are not widely documented, this species is threatened by development, road maintenance, cattle ranches, recreational activities (especially off-road vehicle), and other threats in some places, though there is insufficient data, including anecdotal accounts, to understand scope and severity of threats for this species (NatureServe 2025). However, their overall impact is likely negligible given the species' tolerance of light disturbance, as well as no obvious intrinsic vulnerabilities.
Ecology & Habitat

Habitat

Pediomelum castoreum grows in "sand or sandy soils, open desert scrub communities" (FNA 2023).
Terrestrial Habitats
Shrubland/chaparralDesert
Other Nations (1)
United StatesN3
ProvinceRankNative
CaliforniaS2Yes
NevadaS2Yes
ArizonaS1Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentUnknownSerious or 31-70% pop. declineHigh (continuing)
2 - Agriculture & aquacultureUnknownUnknownHigh (continuing)
2.3 - Livestock farming & ranchingUnknownUnknownHigh (continuing)
4 - Transportation & service corridorsUnknownSerious - moderateHigh (continuing)
4.1 - Roads & railroadsUnknownSerious - moderateHigh (continuing)
4.2 - Utility & service linesUnknownModerate or 11-30% pop. declineHigh (continuing)
6 - Human intrusions & disturbanceUnknownSerious - moderateHigh (continuing)
6.1 - Recreational activitiesUnknownSerious - moderateHigh (continuing)

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)No
Roadless Areas (1)
Nevada (1)
AreaForestAcres
PotosiHumboldt-Toiyabe National Forest5,145
References (8)
  1. Flora of North America Editorial Committee (FNA). 2023. Flora of North America north of Mexico. Vol. 11. Magnoliophyta: Fabaceae, parts 1+2. Oxford Univ. Press, New York. xxvii + 1108 pp.
  2. Global Biodiversity Information Facility (GBIF). 2025. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2025).
  3. iNaturalist. 2025. Online. Available: https://www.inaturalist.org (accessed 2025).
  4. Kartesz, J.T. 1988. A flora of Nevada. Ph.D. dissertation. Univ. of Nevada, Reno. 3 volumes. 1729 pp.
  5. 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.
  6. NatureServe. 2025. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  7. NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2024. Version: 1.1.1 (released Oct 01, 2024).
  8. Southwest Environmental Information Network (SEINet). 2025. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2025).