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Montana Field Guide

Montana Field Guides

Daggett Rockcress - Boechera demissa
Other Names:  Arabis demissa

Species of Concern

Global Rank: G5
State Rank: S1S3
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank: 3
C-value:

External Links






State Rank Reason (see State Rank above)
Daggett rockcress is at the northern edge of its range in Montana, where it is known only from the vicinity of the Pryor Mountains and adjacent Bighorn Canyon. Detailed survey information for most occurrences is lacking.
 
General Description
Daggett rockcress is a perennial with several lax or decumbent stems reaching 10-30 cm tall and untoothed, pointed basal leaves that are lance- or narrowly spoon-shaped and about 1.5 cm long. The stem leaves are 5-10 mm long and stalkless, with a pair of small lobes at the base; the lower stem and leaves are usually - though not always - sparsely hairy with large simple and forked hairs. Flowers consist of 4 erect, greenish or purple-tinged sepals, 4 spreading, white to purplish, spatula-shaped petals (4.5-6.5 mm long and 1.5-2 mm wide), 6 stamens, and a single pistil. The long, slender pods (siliques) are 2-4 cm long on stalks that are 4-7 mm and arch downward from the stem, resulting in the siliques hanging from the main stem in a descending or pendulous position. The flattened, round, wingless seeds form one row in each of the 2 capsule chambers (Rollins 1993).

Phenology
Flowering takes place in May, and fruits mature in June.

Diagnostic Characteristics
Arabis holboellii, A. microphylla, A. sparsiflora and A. lemmonii also have spreading or pendulous fruits, but A. demissa is the only one that has leaves with sparse hair on leaf surfaces and leaf margins that are merely ciliate rather than densely hairy. Montana plants are var. languida

Species Range
Present
 


Range Comments
NV to MT south to AZ, UT and CO (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Summary of Observations Submitted for Montana
Number of Observations: 6

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Habitat
This rockcress occurs in the foothills of the Pryor Mountains (Lesica et al. 1998) and in the Bighorn Canyon National Recreation Area. It grows in canyon bottoms and on outwash plains with dry, stony soils derived from limestone, often in Juniperus osteosperma woodland but also in limber pine woodlands and sagebrush steppe. Other prominent species in its habitat include Agropyron spicatum and Ribes cereum.

Ecological Systems Associated with this Species

Ecology
Like most member of the genus, Arabis demissa occurs in sites with sparse vegetation, suggesting that it is a poor competitor for light, water, or nutrients.

Management
A. demissa grows in semi-arid grasslands and woodlands that are generally grazed, however grazing is unlikely to have adverse effects because the plants are probably unpalatable and would benefit from reduced competition.

References
  • Additional ReferencesLegend:   View Online Publication
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    • Knight, D. H., G. P. Jones, Y. Akashi, and R. W. Myers. 1987. Vegetation ecology in the Bighorn Canyon National Recreation Area. Unpublished report prepared for the USDI National Park Service and University of Wyoming-National Park Service Research.
    • Lesica, P., M. T. Lavin, and P. F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Lesica, P., P. Husby, and S. V. Cooper. 1998. Noteworthy collections: Montana. Madrono 45:328-330.
    • Rollins, R. C. 1993. The Cruciferae of Continental North America: systematics of the mustard family from the Arctic to Panama. Stanford University Press, Stanford, California. 976 pp.
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Citation for data on this website:
Daggett Rockcress — Boechera demissa.  Montana Field Guide.  .  Retrieved on , from