Taxon Report

Arabis aculeolata Greene

Waldo rockcress

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Taxon Summary

Arabis aculeolata, commonly known as Waldo rockcress, is a perennial herb in the Brassicaceae that is found in California and elsewhere. It occurs within Broadleafed upland forest, Lower montane coniferous forest, and Upper montane coniferous forest, growing at elevations from 410 to 1800 meters. Arabis aculeolata is ranked 2B.2, Plants Rare, Threatened, or Endangered in California, But More Common Elsewhere; Moderately threatened in California.

Classification


Scientific Name:	Arabis aculeolata Greene
Common Name:	Waldo rockcress
Family:	Brassicaceae
Element Code:	PDBRA06010
USDA Plants Symbol:	ARAC4
Synonyms/Other Names:

Ecology and Life History


Lifeform:	perennial herb
Blooming Period: Apr-Jun	Apr-Jun
Elevation:	410-1800 (1345-5905)
General Habitats:	Broadleafed upland forest, Lower montane coniferous forest, Upper montane coniferous forest
Microhabitat:	Serpentine
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	2B.2
Global Rank:	G4
State Rank:	S2
State List:	None
Fed List:	None
Other Status:	SB_BerrySB
CRPR Changes:	changed from 2.2 to 2B.2 on 2012-04-11

Occurrence Data from the CNDDB


Total Occurrences:	8
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	0
Fair (C)	0
Poor (D)	0
None (X)	0
Unknown (U)	8

Location


California Endemic: False
California Counties and Islands: Name (Code)
Del Norte (DNT), Siskiyou (SIS)
Quads: Name (Quad Code)
Clear Creek (4112364), Devils Punchbowl (4112376), Hamburg (4112371), High Divide (4112481), High Plateau Mtn. (4112388), Kangaroo Mtn. (4112382), Preston Peak (4112375), Shelly Creek Ridge (4112387)

Threat List Data from the CNDDB


Threat List Total:	2
EOs with Threat Listed:	Total EOs	% of EOs
	2	25 %
Logging	2	25%
Erosion/runoff	1	12%

Notes



On watch list in OR.
Threats:
Threatened by logging and mining.
Taxonomy:
Not in TJM 2.

Selected References

Proposed retention as CRPR 2.2 (2012)

Leaflets of Botanical Observation and Criticism 2:69-88 (1910)

Rhodora 43(511):352-353 (1941)

Arabis aculeolata profile for potential Species of Conservation Concern evaluation (2018)

Contributions from the Gray Herbarium 204:151 (1973)

Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 1 November 2025].