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Lomatium watsonii

(Coult. & Rose) Coult. & Rose

Watson's Desert-parsley

G3Vulnerable Found in 6 roadless areas NatureServe Explorer →
G3VulnerableGlobal Rank
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.133469
Element CodePDAPI1B230
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single nation
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderApiales
FamilyApiaceae
GenusLomatium
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 Date2026-02-04
Change Date2026-02-04
Edition Date2026-02-04
Edition AuthorsSoteropoulos (2026)
Threat ImpactUnknown
Range Extent5000-20,000 square km (about 2000-8000 square miles)
Number of Occurrences21 - 80
Rank Reasons
Lomatium watsonii is a perennial herb found in open, rocky flats or gravelly sites on hillsides in grasslands, scrublands (often with sagebrush), and woodlands. It is endemic to the northwestern United States east of the Cascade Range, along the eastern foothills, from central Washington south to north-central Oregon. There are at least 30, but fewer than 81, occurrences, which face threats from grazing, herbicide use, and recreational activities (especially off-road vehicles). 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
Lomatium watsonii is endemic to the northwestern United States east of the Cascade Range, along the eastern foothills, from central Washington (Chelan, Kittitas, Yakima, and Klickat counties) south to north-central Oregon (Gilliam, Hood River, Jefferson, and Wasco counties) (FNA 2024, Giblin and Legler 2026, OSU 2026). Range extent was estimated to be approximately 17,000 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 over 30, but fewer than 81, occurrences rangewide (RARECAT 2025, GBIF 2026, iNaturalist 2026, NatureServe 2026, SEINet 2026).
Threat Impact Comments
Although threats are not widely documented, this species is threatened by grazing, herbicide use, and recreational activities (especially off-road vehicles), though there is insufficient data, including anecdotal accounts, to understand scope and severity of threats for this species (NatureServe 2026).
Ecology & Habitat

Habitat

Lomatium watsonii grows on open, rocky flats or gravelly sites on hillsides in grasslands, scrublands (often with sagebrush), and woodlands, on basalt-derived substrates, and from valleys to subalpine elevations, ranging from 600 to 1900 m (FNA 2024, Giblin and Legler 2026, OSU 2026).

Reproduction

This species flowers from mid March to early April and fruits from April to June (FNA 2024).
Terrestrial Habitats
Forest/WoodlandWoodland - ConiferShrubland/chaparralGrassland/herbaceousBarrens
Other Nations (1)
United StatesN3
ProvinceRankNative
OregonS1Yes
WashingtonSNRYes
Threat Assessments
ThreatScopeSeverityTiming
2 - Agriculture & aquacultureUnknownUnknownHigh (continuing)
2.3 - Livestock farming & ranchingUnknownUnknownHigh (continuing)
6 - Human intrusions & disturbanceUnknownUnknownHigh (continuing)
6.1 - Recreational activitiesUnknownUnknownHigh (continuing)
9 - PollutionUnknownUnknownHigh (continuing)
9.3 - Agricultural & forestry effluentsUnknownUnknownHigh (continuing)
9.3.3 - Herbicides and pesticidesUnknownUnknownHigh (continuing)

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)Yes
Roadless Areas (6)
Washington (6)
AreaForestAcres
Blue SlideWenatchee National Forest17,505
Devils GulchWenatchee National Forest24,419
Lion RockWenatchee National Forest4,692
Norse PeakWenatchee National Forest10,169
TeanawayWenatchee National Forest72,849
Thorp Mtn.Wenatchee National Forest22,717
References (9)
  1. Flora of North America Editorial Committee (FNA). 2024. Flora of North America north of Mexico. Vol. 13. Magnoliophyta: Geraniaceae to Apiaceae. Oxford Univ. Press, New York. xxiv + 566 pp.
  2. Giblin, D.E., and B.S. Legler (eds.). 2003+. WTU Image Collection Web Site: Vascular Plants, MacroFungi, & Lichenized Fungi of Washington State. University of Washington Herbarium. Online. Available: http://biology.burke.washington.edu/herbarium/imagecollection.php.
  3. Global Biodiversity Information Facility (GBIF). 2026. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2026).
  4. iNaturalist. 2026. Online. Available: https://www.inaturalist.org (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. NatureServe. 2026. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  7. Oregon State University (OSU). 2026. Oregon Flora website. Oregon State University Herbarium at Oregon State University. Online. Available: https://oregonflora.org/ (accessed 2026).
  8. <p>NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2025. Version: 2.1.1 (released April 04, 2025).</p>
  9. Southwest Environmental Information Network (SEINet). 2026. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2026).