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Cardamine constancei

Detling

Constance's Bittercress

G3Vulnerable Found in 1 roadless area NatureServe Explorer →
G3VulnerableGlobal Rank
HighThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.157986
Element CodePDBRA0K080
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single state or province
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderCapparales
FamilyBrassicaceae
GenusCardamine
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 Date2025-03-14
Change Date1985-09-06
Edition Date2025-03-14
Edition AuthorsMancuso, M./Gries, D., rev. N. Ventrella (2025)
Threat ImpactHigh
Range Extent5000-20,000 square km (about 2000-8000 square miles)
Number of Occurrences21 - 80
Rank Reasons
Endemic to Idaho in the western United States, Cardamine constancei is a perennial forb found primarily along the St. Joe, Selway, and Clearwater rivers of Clearwater, Idaho, Nez Perce, and Shoshone counties. The species is known from an estimated 76 extant occurrences. Mining activities have modified the landscape, but the most widespread modification to the plant's habitat has been from many years of timber harvest and associated road building, along with fire suppression, and stand-replacing wildfires. This species is adapted to light disturbance and requires open to semi-open forest canopies in order to produce flowers.
Range Extent Comments
Cardamine constancei occurs in the western United Sates, where it is endemic to the northern Rocky Mountains of Idaho (Brunsfeld and Sullivan 2005). Specifically, it occurs along the St. Joe, Selway, and Clearwater rivers of Clearwater, Idaho, Nez Perce, and Shoshone counties (Schaack 1988, FNA 2010). Range extent was estimated using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1984 and 2025 (RARECAT 2024, CPNWH 2025, iNaturalist 2025, NatureServe 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 76 occurrences rangewide (RARECAT 2024, CPNWH 2025, iNaturalist 2025, NatureServe 2025). The Idaho Natural Heritage Program tracks 119 occurrences of this species, though 32 of these have not been monitored since prior to 1984 and are considered historical (NatureServe 2025).
Threat Impact Comments
The Idaho Native Plant Society lists canopy, roads, logging, weeds, and recreation as threats to Cardamine constancei in their most recent rare plant list (INPS 2024). Mining and road building activities have modified the landscape, particularly around the Kellogg region of Shoshone County (Schaack 1988). The most widespread modification to Cardamine constancei habitat has been from many years of timber harvest and associated road building, as well as fire suppression (Mancuso, pers. comm, 1999). This species is dependent on periodic underburns that open the canopy, but cannot survive in places where no surviving trees remain to provide shade (Lichhardt and Moseley 1994). High-intensity, stand-replacing wildfire is therefore also a threat to this species, and it is possible that Cardamine constancei was extirpated from Lochsa Canyon by a series of large fires. Some insect predation to leaves is known to occur (Lichthardt 1995).
Ecology & Habitat

Habitat

Cardamine constancei occurs on "moist cliffs, wooded creek bottoms, shaded draws, hillsides, moist woods, mixed coniferous forests, [and] granitic soils" from 400-600 m in elevation (FNA 2010). It is typically associated with moist coniferous woods along rivers (Rollins 1993). Vegetation types include the western redcedar (Thuja plicata) and western hemlock (Tsuga heterophylla) series, especially western redcedar/maidenhair fern (Thuja plicata/Adiantum pedatum), western redcedar/oakfern (Thuja plicata/Gymnocarpium dryopteris), and western hemlock/wild ginger (Tsuga heterophylla/Asarum caudatum) habitat types (Lichthardt 1995).

Reproduction

Cardamine constancei produces flowers from May to June, though flowering is a rare event for this species (Lichthardt 1995).
Terrestrial Habitats
Woodland - Conifer
Palustrine Habitats
Riparian
Other Nations (1)
United StatesN3
ProvinceRankNative
IdahoS3Yes
Threat Assessments
ThreatScopeSeverityTiming
3 - Energy production & miningUnknownUnknownInsignificant/negligible or past
3.2 - Mining & quarryingUnknownUnknownInsignificant/negligible or past
4 - Transportation & service corridorsUnknownUnknownHigh (continuing)
4.1 - Roads & railroadsUnknownUnknownHigh (continuing)
5 - Biological resource useUnknownUnknownHigh (continuing)
5.3 - Logging & wood harvestingUnknownUnknownHigh (continuing)
5.3.4 - Unintentional effects: large scale (species being assessed is not the target) [harvest]UnknownUnknownHigh (continuing)
6 - Human intrusions & disturbanceUnknownUnknownHigh (continuing)
6.1 - Recreational activitiesUnknownUnknownHigh (continuing)
7 - Natural system modificationsLarge (31-70%)Serious or 31-70% pop. declineHigh (continuing)
7.1 - Fire & fire suppressionLarge (31-70%)Serious or 31-70% pop. declineHigh (continuing)
7.1.1 - Increase in fire frequency/intensityRestricted (11-30%)Serious or 31-70% pop. declineHigh (continuing)
7.1.2 - Suppression in fire frequency/intensityLarge (31-70%)Serious - moderateHigh (continuing)
8 - Invasive & other problematic species, genes & diseasesUnknownUnknownHigh (continuing)
8.1 - Invasive non-native/alien species/diseasesUnknownUnknownHigh (continuing)
8.2 - Problematic native species/diseasesUnknownUnknownHigh (continuing)
8.2.1 - Unspecified speciesUnknownUnknownHigh (continuing)

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)No
Roadless Areas (1)
Idaho (1)
AreaForestAcres
West Meadow CreekNez Perce-Clearwater National Forest115,949
References (15)
  1. Brunsfeld, S.J. and J. Sullivan. 2005. A multi-compartmented glacial refugium in the northern Rocky Mountains: evidence from the phylogeography of <i>Cardamine constancei</i> (Brassicaceae). Conservation Genetics: 895-904.
  2. Consortium of Pacific Northwest Herbaria (CPNWH). 2025. Online database of vascular plant specimens from the Pacific Northwest. Online. Available: http://www.pnwherbaria.org/index.php (accessed 2025).
  3. Davis, R.J. 1952. Flora of Idaho. Brigham Young Univ. Press, Provo, UT. 836 pp.
  4. Flora of North America Editorial Committee (FNA). 2010. Flora of North America north of Mexico. Vol. 7. Magnoliophyta: Salicaceae to Brassicaceae. Oxford University Press, New York. xxii + 797 pp.
  5. Idaho Native Plant Society (INPS). 2024. Rare Plant Working Groups, Idaho Rare Plant List. https://idahonativeplants.org/rare-plant-conference/
  6. iNaturalist. 2025. Online. Available: https://www.inaturalist.org (accessed 2025).
  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. Lichthardt, J. 1995. Establishment of monitoring plots for Constance's bittercress (<i>Cardamine constancei</i>). Unpublished report prepared for the Clearwater National Forest. Idaho Department of Fish and Game, Conservation Data Center, Boise, ID. 7 pp.
  9. Lichthardt, J. and R. K. Moseley. 1994. Ecosystem analysis and conservation planning for the Clearwater refugium, Clearwater and Nex Perce National Forests. Unpublished report prepared for the Clearwater and Nez Perce National Forests. Idaho Department of Fish and Game, Conservation Data Center, Boise, ID. 42 pp.
  10. Mancuso, Michael. Botanist, Idaho Conservation Data Center, Boise, Idaho. Personal communication.
  11. NatureServe. 2025. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  12. NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2024. Version: 1.1.1 (released Oct 01, 2024).
  13. North Idaho Rare Plant Working Group. 2013. Unpublished rank calculator spreadsheet for <i>Cardamine constancei</i> version 3.1. Idaho Native Plants Society, Boise, ID.
  14. Rollins, R.C. 1993a. The Cruciferae of continental North America: Systematics of the mustard family from the Arctic to Panama. Stanford Univ. Press, Stanford, California. 976 pp.
  15. Schaack, C.G. 1988. Noteworthy collections. Madrono 35(4):353-359.