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Allium bolanderi

S. Wats.

Bolander's Onion

G4Apparently Secure Found in 14 roadless areas NatureServe Explorer →
G4Apparently SecureGlobal Rank
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.136661
Element CodePMLIL02090
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single nation
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderAsparagales
FamilyAmaryllidaceae
GenusAllium
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
Kartesz (1994 checklist) recognizes two varieties, the typical, var. bolanderi, and var. stenanthum; a third variety (var. mirabile) is sometimes recognized, but Kartesz includes its synonym (A. mirabile) in A. bolanderi. FNA (vol. 26, 2002) includes A. bolanderi var. stenanthum in A. bolanderi var. bolanderi, while Kartesz (1994) treats them as distinct.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2026-02-26
Change Date1996-01-24
Edition Date2026-02-26
Edition AuthorsSoteropoulos (2026)
Threat ImpactUnknown
Range Extent20,000-200,000 square km (about 8000-80,000 square miles)
Number of Occurrences81 - 300
Rank Reasons
Allium bolanderi is an annual herb found in rocky, clay soils, including serpentine soils, in dry openings in grasslands, chaparral, and savannas. It is endemic to the western United States in southwestern Oregon and western California. There are over 81 occurrences, which face threats from development, mining, logging, use of open habitat for slash piles and logging sets, recreation, and fire when plants are not dormant. 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 bolanderi is endemic to the western United States in southwestern Oregon and western California in the Klamath Ranges, Cascade Range Foothills and High Cascade Range, North Coast, North Coast Ranges, south to the San Francisco Bay Area (FNA 2002, Jepson Flora Project 2026, OSU 2026). Range extent was estimated to be approximately 75,000 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 81 occurrences rangewide (RARECAT 2025, GBIF 2026, iNaturalist 2026, NatureServe 2026, SEINet 2026).
Threat Impact Comments
This species is threatened by development, mining, logging, use of open habitat for slash piles and logging sets, recreation, and fire when plants are not dormant, though there is insufficient data, including anecdotal accounts, to understand scope and severity of threats for this species (NatureServe 2026).
Ecology & Habitat

Habitat

Allium bolanderi grows in rocky, clay soils, including serpentine soils, in dry openings in grasslands, chaparral, and savannas (FNA 2002, Jepson Flora Project 2026, OSU 2026).

Reproduction

This taxon flowers from late May to early August (FNA 2002).
Terrestrial Habitats
Shrubland/chaparralSavannaGrassland/herbaceous
Other Nations (1)
United StatesN4
ProvinceRankNative
CaliforniaSNRYes
OregonS3Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentUnknownUnknownHigh (continuing)
3 - Energy production & miningUnknownUnknownHigh (continuing)
3.2 - Mining & quarryingUnknownUnknownHigh (continuing)
5 - Biological resource useUnknownUnknownHigh (continuing)
5.3 - Logging & wood harvestingUnknownUnknownHigh (continuing)
6 - Human intrusions & disturbanceUnknownUnknownHigh (continuing)
6.1 - Recreational activitiesUnknownUnknownHigh (continuing)
6.3 - Work & other activitiesUnknownUnknownHigh (continuing)
7 - Natural system modificationsUnknownUnknownHigh (continuing)
7.1 - Fire & fire suppressionUnknownUnknownHigh (continuing)

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)Yes
Roadless Areas (14)
California (13)
AreaForestAcres
Black ButteMendocino National Forest15,461
Bonanza KingShasta-Trinity National Forest16,402
ChinquapinShasta-Trinity National Forest22,040
Devils RockShasta-Trinity National Forest16,209
KelseyKlamath National Forest3,237
Mt. LassicSix Rivers National Forest6,643
PattisonShasta-Trinity National Forest29,299
Penney RidgeShasta-Trinity National Forest5,226
PortugueseKlamath National Forest18,915
RussianKlamath National Forest21,771
SnoozerKlamath National Forest23,414
UnderwoodSix Rivers National Forest6,591
Weaver BallyShasta-Trinity National Forest829
Oregon (1)
AreaForestAcres
North KalmiopsisSiskiyou National Forests91,560
References (9)
  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. 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. 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).