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Montana Field Guide

Montana Field Guides

Puzzling Rockcress - Sandbergia perplexa
Other Names:  Halimolobos perplexa

Species of Concern

Global Rank: G4
State Rank: S2
* (see State Rank Reason below)

Agency Status
USFWS:
USFS: SENSITIVE
BLM:
MNPS Threat Rank: 2
C-value:

External Links






State Rank Reason (see State Rank above)
Rare in Montana, where it is known only from the very southern end of the Bitterroot Valley on the Bitterroot National Forest. Spotted knapweed is known from at least one of the populations and further spread of invasive weeds at the known occurrences is likely without control measures. Trend data and repeat observations of the known occurrences are lacking.
 
General Description
Puzzling Rockcress is a rosette-forming, short-lived perennial with 1 to several erect stems that are 15-40 cm high and which arise from a simple or branched rootcrown. The lance-shaped basal leaves are 2-4 cm long and have petioles and deeply toothed to shallowly lobed margins. Upper stem leaves are smaller and sessile, and the foliage is covered with branched hairs. Stalked flowers occur at the stem tips in a compact, unbranched inflorescence that expands as the fruits mature. Each flower has 4 separate sepals, 4 separate, white petals that are 3-6 mm long, and 4 long and 2 short stamens. The style is ca. 1 mm long. The hairy, linear capsules, or siliques, are 1-2 cm long with a circular cross-section and are borne on erect to ascending stalks that are 10-17 mm long.

Phenology
Flowering in May-June, fruiting in June.

Diagnostic Characteristics
Leaves of H. virgata clasp the stem, and the siliques are glabrous. Species of Arabis usually have flattened siliques.


Species Range
Montana Range

Click the legend blocks above to view individual ranges.
 


Range Comments
Endemic to east-central ID and adjacent MT; one collection from southern Ravalli Co. and reported for Beaverhead Co. (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Summary of Observations Submitted for Montana
Number of Observations: 39

(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
Sparsely vegetated, gravelly slopes of sagebrush steppe, mountain mahogany woodlands, or pine woodlands in the montane zone.
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habit Model available.

To learn how these Models were created see http://mtnhp.org/models

Ecological Systems Associated with this Species

References
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Citation for data on this website:
Puzzling Rockcress — Sandbergia perplexa.  Montana Field Guide.  .  Retrieved on , from