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Allium nevii

S. Wats.

Nevius' Garlic

G3Vulnerable Found in 5 roadless areas NatureServe Explorer →
G3VulnerableGlobal Rank
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.143698
Element CodePMLIL022T0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single nation
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderAsparagales
FamilyAmaryllidaceae
GenusAllium
Synonyms
Allium douglasii var. nevii(S. Wats.) Ownbey & Mingrone
Other Common Names
Nevius' Onion (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 Date2026-01-12
Change Date2026-01-12
Edition Date2026-01-08
Edition AuthorsA. Olivero (2002), rev. Soteropoulos (2026)
Threat ImpactUnknown
Range Extent5000-20,000 square km (about 2000-8000 square miles)
Number of Occurrences21 - 80
Rank Reasons
Allium nevii is a perennial forb found in vernally wet meadows and along streams, and also in seasonally moist scablands. It occurs in the northwestern United States in central Washington south to north-central Oregon on the eastern slope of the Cascades crest. There are over 50 occurrences, which face threats from development, conversion to agriculture and rangeland, grazing, work and silvicultural activities, including soil compaction from use as log storage and staging sets, hydrological alteration, competition from nonnative species, browsing by deer and elk, and drought leading to habitat drying before flowering. 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
Allium nevii occurs in the northwestern United States in Washington and Oregon on the eastern slope of the Cascades crest in central Washington from Chelan County south to Jefferson and Wasco counties, Oregon (FNA 2002, McNeal 2002, Hitchcock and Cronquist 2018, 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 50 occurrences rangewide (RARECAT 2025, GBIF 2026, iNaturalist 2026, NatureServe 2026, SEINet 2026).
Threat Impact Comments
This species is threatened by development, conversion to agriculture and rangeland, grazing, work and silvicultural activities, including soil compaction from use as log storage and staging sets, hydrological alteration, competition from nonnative species (including cheatgrass and bulbous bluegrass), browsing by deer and elk, and drought leading to habitat drying before flowering, though there is insufficient data, including anecdotal accounts, to understand scope and severity of threats for this species (McNeal 2002, NatureServe 2025).
Ecology & Habitat

Habitat

Allium nevii grows in heavy, rocky soils, in vernally wet meadows and along streams, and also in seasonally moist scablands (FNA 2002, Giblin and Legler 2026, OSU 2026).

Reproduction

This species flowers from May to July (FNA 2002).
Terrestrial Habitats
Grassland/herbaceousBarrens
Palustrine Habitats
HERBACEOUS WETLANDRiparian
Other Nations (1)
United StatesN3
ProvinceRankNative
WashingtonSNRYes
OregonS2Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentUnknownUnknownUnknown
2 - Agriculture & aquacultureUnknownUnknownUnknown
2.1 - Annual & perennial non-timber cropsUnknownUnknownUnknown
2.3 - Livestock farming & ranchingUnknownUnknownUnknown
5 - Biological resource useUnknownUnknownUnknown
5.3 - Logging & wood harvestingUnknownUnknownUnknown
6 - Human intrusions & disturbanceUnknownUnknownUnknown
6.3 - Work & other activitiesUnknownUnknownUnknown
7 - Natural system modificationsUnknownUnknownUnknown
7.2 - Dams & water management/useUnknownUnknownUnknown
8 - Invasive & other problematic species, genes & diseasesUnknownUnknownUnknown
8.1 - Invasive non-native/alien species/diseasesUnknownUnknownUnknown
8.1.1 - Unspecified speciesUnknownUnknownUnknown
8.2 - Problematic native species/diseasesUnknownUnknownUnknown
8.2.2 - Named speciesUnknownUnknownUnknown
11 - Climate change & severe weatherUnknownUnknownUnknown
11.2 - DroughtsUnknownUnknownUnknown

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)Yes
Roadless Areas (5)
Washington (5)
AreaForestAcres
Blue SlideWenatchee National Forest17,505
Devils GulchWenatchee National Forest24,419
Lion RockWenatchee National Forest4,692
ManastashWenatchee National Forest11,155
NaneumWenatchee National Forest4,508
References (13)
  1. Flora of North America Editorial Committee (FNA). 2002a. Flora of North America north of Mexico. Vol. 26. Magnoliophyta: Liliidae: Liliales and Orchidales. Oxford Univ. Press, New York. xxvi + 723 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. Hitchcock, C.L., and A. Cronquist. 1974. Flora of the Pacific Northwest: An illustrated manual. 2nd printing, with corrections. Univ. Washington Press, Seattle. xix + 730 pp.
  5. Hitchcock, C.L., and A. Cronquist. 2018. Flora of the Pacific Northwest: An illustrated manual. Edited by D.E. Giblin, B. S. Legler, P.F. Zika, and R. G. Olmstead. 2nd edition. Univ. Washington Press, Seattle. xiii + 822 pp.
  6. iNaturalist. 2026. Online. Available: https://www.inaturalist.org (accessed 2026).
  7. 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.
  8. McNeal, D. W. 2002. Report on <i>Allium</i>. Columbia Basin Scientific Assessment Project. University of the Pacific, Stockton, CA. Available: <u></u>. Accessed 2002, October 31.
  9. NatureServe. 2026. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  10. Oregon State University (OSU). 2026. Oregon Flora website. Oregon State University Herbarium at Oregon State University. Online. Available: https://oregonflora.org/ (accessed 2026).
  11. Peterson, P.M., C.R. Annable, and L.H. Rieseberg. 1988. Systematic relationships and nomenclatural changes in the Allium douglasii complex (Alliaceae). Systematic Botany. 13(2):207-214.
  12. <p>NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2025. Version: 2.1.1 (released April 04, 2025).</p>
  13. Southwest Environmental Information Network (SEINet). 2026. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2026).