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Home/Species/ Tweedy's Ivesia

Ivesia tweedyi

Rydb.

Tweedy's Ivesia

G4Apparently Secure Found in 2 roadless areas NatureServe Explorer →
G4Apparently SecureGlobal Rank
LowThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.146764
Element CodePDROS0X0M0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single nation
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderRosales
FamilyRosaceae
GenusIvesia
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 Date2025-05-14
Change Date1985-09-06
Edition Date2025-05-14
Edition AuthorsJohnson, J. (2025)
Threat ImpactLow
Range Extent20,000-200,000 square km (about 8000-80,000 square miles)
Number of Occurrences21 - 80
Rank Reasons
Ivesia tweedyi is a perennial herb found in subalpine areas of the northern Cascade and Rocky Mountains of the northwestern United States. While documentation for this species is limited, this habitat faces few threats. With a wide range and low threats, this species is apparently secure.
Range Extent Comments
Ivesia tweedyi is found in the northwestern United States from the Cascade Range in central Washington to northern Idaho, and barely enters western Montana in Mineral County (FNA 2014). Range extent was estimated using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1984 and 2025 (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).
Occurrences Comments
By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1984 and 2025, it is estimated that there are 37 occurrences rangewide (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).
Threat Impact Comments
While threats have not been documented for this species, it is likely to experience low levels of recreational impacts like other alpine species in Washington, Idaho, and Montana, such as Penstemon flavescens, Draba oligosperma, and Polemonium viscosum (NatureServe 2025).
Ecology & Habitat

Habitat

Ivesia tweedyi grows on "dry, gravelly to rocky flats, slopes, alpine ridges, often on serpentine, in subalpine conifer woodlands" (FNA 2014).
Terrestrial Habitats
Forest EdgeAlpine
Other Nations (1)
United StatesN4
ProvinceRankNative
MontanaSNRYes
IdahoS2Yes
WashingtonSNRYes
Threat Assessments
ThreatScopeSeverityTiming
6 - Human intrusions & disturbanceUnknownSlight or 1-10% pop. declineHigh (continuing)
6.1 - Recreational activitiesUnknownSlight or 1-10% pop. declineHigh (continuing)

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)No
Roadless Areas (2)
Washington (2)
AreaForestAcres
Alpine Lakes Adj.Wenatchee National Forest57,104
TeanawayWenatchee National Forest72,849
References (7)
  1. Flora of North America Editorial Committee (FNA). 2014b. Flora of North America north of Mexico. Vol. 9. Magnoliophyta: Picramniaceae to Rosaceae. Oxford University Press, New York. xxiv + 713 pp.
  2. Global Biodiversity Information Facility (GBIF). 2025. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2025).
  3. iNaturalist. 2025. Online. Available: https://www.inaturalist.org (accessed 2025).
  4. 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.
  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).