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Home/Species/ Howell's Adder's-tongue

Erythronium howellii

S. Wats.

Howell's Adder's-tongue

G3Vulnerable Found in 1 roadless area NatureServe Explorer →
G3VulnerableGlobal Rank
HighThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.132018
Element CodePMLIL0U080
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single nation
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderLiliales
FamilyLiliaceae
GenusErythronium
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
FNA (vol. 26, 2002) expands the concept of Erythronium citrinum to include E. howellii, while Kartesz (1994) here treats them as distinct.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2026-03-13
Change Date2026-03-13
Edition Date2026-03-13
Edition Authors???, rev. L. Morse (1998), rev. Soteropoulos (2026)
Threat ImpactHigh
Range Extent5000-20,000 square km (about 2000-8000 square miles)
Number of Occurrences21 - 80
Rank Reasons
This taxon is a perennial herb found in open, dry woodlands and shrubby slopes, often on serpentine. It is endemic to the western United States in the Siskiyou Mountains of the Klamath Ranges of southwestern Oregon and northwestern California. There are 41 estimated occurrences, which face threats from residential development, mining, road construction and maintenance, logging and timber harvest practices, and recreational activities.
Range Extent Comments
This taxon is endemic to the western United States in the Siskiyou Mountains of the Klamath Ranges of southwestern Oregon (Curry, Jackson, and Josephine counties) and northwestern California (Del Norte, Siskiyou, and Trinity counties) (Jepson Flora Project 2026, OSU 2026). Range extent was estimated to be 14,200 square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025 (RARECAT 2025, GBIF 2026, iNaturalist 2026, NatureServe 2026, SEINet 2026).
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 41 occurrences rangewide (RARECAT 2025, GBIF 2026, iNaturalist 2026, NatureServe 2026, SEINet 2026).
Threat Impact Comments
This taxon is threatened by residential development, mining, road construction and maintenance, logging and timber harvest practices, and recreational activities (CNPS 2026, NatureServe 2026).
Ecology & Habitat

Habitat

This taxon grows in open, dry woodlands (lower montane coniferous forests and North Coast coniferous forests) and less often in shrubby, chapparal slopes, often on serpentine but on a variety of substrates, including gravelly colluvium (CNPS 2026, Jepson Flora Project 2026, OSU 2026).

Reproduction

This taxon flowers from March to May (Jepson Flora Project 2026). Seeds are dispersed by ants (Guitian et al. 2003 in CNPS 2026).
Terrestrial Habitats
Forest/WoodlandForest - ConiferWoodland - ConiferShrubland/chaparral
Other Nations (1)
United StatesN3
ProvinceRankNative
CaliforniaS2Yes
OregonS3Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentRestricted (11-30%)Serious or 31-70% pop. declineHigh - moderate
1.1 - Housing & urban areasRestricted (11-30%)Serious or 31-70% pop. declineHigh - moderate
3 - Energy production & miningLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
3.2 - Mining & quarryingLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
4 - Transportation & service corridorsLarge - restrictedModerate or 11-30% pop. declineHigh (continuing)
4.1 - Roads & railroadsLarge - restrictedModerate or 11-30% pop. declineHigh (continuing)
5 - Biological resource usePervasive - largeModerate or 11-30% pop. declineHigh (continuing)
5.3 - Logging & wood harvestingPervasive - largeModerate or 11-30% pop. declineHigh (continuing)
6 - Human intrusions & disturbanceLarge - restrictedModerate - slightHigh (continuing)
6.1 - Recreational activitiesLarge - restrictedModerate - slightHigh (continuing)

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)No
Roadless Areas (1)
Oregon (1)
AreaForestAcres
South KalmiopsisSiskiyou National Forests104,477
References (10)
  1. California Native Plant Society (CNPS), Rare Plant Program. 2026. Inventory of Rare and Endangered Plants of California, online edition, v9.5. Online. Available: https://www.rareplants.cnps.org (accessed 2026).
  2. Global Biodiversity Information Facility (GBIF). 2026. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2026).
  3. iNaturalist. 2026. Online. Available: https://www.inaturalist.org (accessed 2026).
  4. Jepson Flora Project (eds.) 2026. Jepson eFlora. Online. Available: https://ucjeps.berkeley.edu/eflora/ (accessed 2026).
  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. Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.
  7. NatureServe. 2026. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  8. Oregon State University (OSU). 2026. Oregon Flora website. Oregon State University Herbarium at Oregon State University. Online. Available: https://oregonflora.org/ (accessed 2026).
  9. <p>NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2025. Version: 2.1.1 (released April 04, 2025).</p>
  10. Southwest Environmental Information Network (SEINet). 2026. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2026).