Daggett Rockcress -
Arabis demissa var. languida, Boechera demissa var. languida
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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.
Daggett Rockcress is a small perennial with one to several clusters of basal leaves arising from a simple or branched rootcrown. One to several, usually unbranched, often decumbant flowering stems which stand 1-3 dm high are present. The lance or narrowly spoon-shaped basal leaves have entire margins and pointed tips and are about 1.5 cm long. The scattered stem leaves are 5-10 mm long, stalkless, and have small auricles at their bases. The basal leaves, lower stem, and lower stem leaves are usually sparsely hairy with large simple and forked hairs, though in rare cases, they may be almost hairless. The flowers have 4 erect, greenish or purple-tinged sepals, 4 spreading, white to purplish, spatula-shaped petals which are 4.5-6.5 mm long and 1.5-2 mm wide, 6 stamens, and a single pistil. The siliques are 2-4 cm long and are descending or pendulous, arising from 4-7 mm long pedicels which arch downward from the stem. The flattened, round, wingless seeds are in one row in each of the 2 chambers of the fruit.
Flowering takes place in May, and fruits mature in June.
Arabis holboellii, A. microphylla, A. sparsiflora and A. lemmonii also have spreading or pendulous fruits, but Boechera languida is the only one that has leaves with sparse hair on leaf surfaces and leaf margins that are merely ciliate rather than densely hairy.
Regional endemic of central and southern Wyoming, Colorado, Utah, and Nevada.
Observations in Montana Natural Heritage Program Database
Number of Observations:
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(Observations spanning multiple months or years are excluded from time charts)
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.
Like most member of the genus,
Boechera languida occurs in sites with sparse vegetation, suggesting that it is a poor competitor for light, water, or nutrients.
Boechera languida 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.
Threats or Limiting Factors
STATE THREAT SCORE REASON Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).
Literature Cited Above
Legend: View Online Publication Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p. Additional References
Legend: View Online Publication Do you know of a citation we're missing? Fertig, W. 1992. Checklist of the vascular plant flora of the west slope of the Wind River Range and status report on sensitive plant species occurring in the Rock Springs District, Bureau of Land Management. Unpublished report to the BLM, Rock Springs District. Rocky Mountain Herbarium, University of Wyoming. 60 pp. 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. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 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.