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Castilleja tenuis

(Heller) Chuang & Heckard

Hairy Owl's-clover

G5Secure Found in 55 roadless areas NatureServe Explorer →
G5SecureGlobal Rank
Identity
Unique IDELEMENT_GLOBAL.2.149875
Element CodePDSCR0D440
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderScrophulariales
FamilyOrobanchaceae
GenusCastilleja
Synonyms
Orthocarpus tenuisA. Heller
Other Common Names
Castilléjie grêle (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.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-03-26
Change Date1990-01-16
Edition Date2025-03-26
Edition AuthorsJohnson, J. (2025)
Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Number of Occurrences> 300
Rank Reasons
Castilleja tenuis is an annual herb found in seasonal wetlands in the western United States and Canada. With a large range extent, more than 500 occurrences, and broad habitat preferences for abundant habitat, this species is considered secure.
Range Extent Comments
Castilleja tenuis is restricted to the east side of the Cascade Range in British Columbia and Washington and also occurs west of the Cascade-Sierra axis in the more arid terrain of California and Oregon. It was collected as a waif in Skagway, Alaska, a century ago (FNA 2019). Range extent was estimated using herbarium specimens and photo-based observations documented between 1994 and 2025 (RARECAT 2024, GBIF 2025, iNaturalist 2025, SEINet 2025).
Occurrences Comments
By applying a 1 km separation distance to herbarium records and photo-based observations documented between 1994 and 2025, there are estimated to be more than 500 occurrences rangewide (RARECAT 2024, GBIF 2025, iNaturalist 2025, SEINet 2025).
Threat Impact Comments
Although threats are not widely documented, Castilleja tenuis is potentially threatened by development, road maintenance, invasive species, and other threats in some places. However, their overall impact is likely negligible given the species' broad range, large number of occurrences, tolerance of light disturbance, and affinity for typically abundant habitats, as well as no obvious intrinsic vulnerabilities.
Ecology & Habitat

Habitat

Castilleja tenuis grows in moist flats, vernal pools, springs, damp meadows and ditches, riparian zones, sometimes over serpentine (FNA 2019).
Terrestrial Habitats
Grassland/herbaceous
Palustrine Habitats
HERBACEOUS WETLANDRiparian
Other Nations (2)
CanadaN1
ProvinceRankNative
British ColumbiaS1Yes
United StatesN5
ProvinceRankNative
WashingtonSNRYes
IdahoSNRYes
OregonSNRYes
AlaskaSNRYes
UtahSNRYes
CaliforniaSNRYes
NevadaS4Yes
Threat Assessments
ThreatScopeSeverityTiming
Unknown/undeterminedUnknownUnknownUnknown

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Plant Characteristics
DurationANNUAL
Economic Value (Genus)No
Roadless Areas (55)
California (36)
AreaForestAcres
Bald MountainTahoe National Forest5,832
Bald RockPlumas National Forest4,675
Bear Camp FlatModoc National Forest2,471
Bell MeadowStanislaus National Forest7,968
Buckeye RidgeHumboldt-Toiyabe National Forest2,241
Caples CreekEldorado National Forest17,854
Carson - IcebergStanislaus National Forest56,430
Castle PeakTahoe National Forest14,974
Chips CreekLassen National Forest29,089
Devil's Gate (CA)Humboldt-Toiyabe National Forest9,946
DomeStanislaus National Forest11,085
Domeland Add.Sequoia National Forest3,046
Duncan CanyonTahoe National Forest8,621
EagleStanislaus National Forest16,116
East YubaTahoe National Forest17,968
Granite ChiefTahoe National Forest6,546
Grouse LakesTahoe National Forest19,085
Hoover - Green Ck NoHumboldt-Toiyabe National Forest7,155
Hoover - NorthHumboldt-Toiyabe National Forest1,574
Middle ForkPlumas National Forest29,278
Middle YubaTahoe National Forest7,379
Mt. JacksonHumboldt-Toiyabe National Forest20,721
Mt. BidwellModoc National Forest11,687
Mt. EddyShasta-Trinity National Forest7,232
Mt. VidaModoc National Forest7,771
North Fork SmithSix Rivers National Forest37,898
PacksaddleSix Rivers National Forest3,862
PyramidEldorado National Forest24,347
Robinson PeakHumboldt-Toiyabe National Forest5,835
San JoaquinSierra National Forest22,474
ScodiesSequoia National Forest725
South SierraSequoia National Forest8,008
Steele SwampModoc National Forest18,958
Tragedy - Elephants BackEldorado National Forest20,866
WaterhouseStanislaus National Forest4,394
WoodpeckerSequoia National Forest11,936
Nevada (1)
AreaForestAcres
McaffieHumboldt-Toiyabe National Forest26,110
Oregon (14)
AreaForestAcres
Calf - Copeland CreekUmpqua National Forest15,696
Crane MountainFremont National Forest23,096
Glacier MountainMalheur National Forest20,661
HellholeUmatilla National Forest65,679
HomesteadWallowa-Whitman National Forest5,817
Imnaha FaceWallowa-Whitman National Forest29,575
Lookout MountainOchoco National Forest14,115
Myrtle SilviesMalheur National Forest11,679
North KalmiopsisSiskiyou National Forests91,560
Shasta CostaSiskiyou National Forests14,420
Sheep DivideWallowa-Whitman National Forest16,201
Silver CreekOchoco National Forest7,952
South KalmiopsisSiskiyou National Forests104,477
Upper Catherine CreekWallowa-Whitman National Forest6,446
Washington (4)
AreaForestAcres
Lion RockWenatchee National Forest4,692
ManastashWenatchee National Forest11,155
QuartzWenatchee National Forest8,550
TaneumWenatchee National Forest26,140
References (7)
  1. Flora of North America Editorial Committee (FNA). 2019. Flora of North America north of Mexico. Vol. 17: Magnoliophyta: Tetrachondraceae to Orobanchaceae. Oxford Univ. Press, New York. xxiv + 737 pp.
  2. Global Biodiversity Information Facility (GBIF). 2025. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2025).
  3. 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.
  4. Munz, P.A., with D.D. Keck. 1959. A California flora. Univ. California Press, Berkeley. 1681 pp.
  5. NatureServe. 2025. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  6. NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2024. Version: 1.1.1 (released Oct 01, 2024).
  7. Southwest Environmental Information Network (SEINet). 2025. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2025).