Community Field Guide
Scientific Name:
Pseudoroegneria spicata - Cushion plant Herbaceous Vegetation
Common Name:
Bluebunch wheatgrass - cushion plant Herbaceous Vegetation
Community Description
Summary:
This association is found in the Tendoy Mountains in southwestern Montana and the Pryor Mountains and adjacent Bighorn Canyon area in south-central Montana. In the Pryor Mountains this type occurs at foothill elevations between 1250-1680 m (4100-5500 feet). In the Tendoy Mountains it has been documented from 2580 m (8450 feet) elevation, but is noted in reconnaissance from 2075-2685 m (6800-8800 feet) elevation. This vegetation occurs on moderately deep gravelly soils from limestone or calcareous sandstone of mesas, ridgetops and saddles and the upper slopes of outwash plains. The primary influencing environmental factor is wind; in most examples of this type wind deflation has produced a gravel paved surface. This herbaceous type is characterized by the presence of short-stature, compact cushion plants of the genera Arenaria, Hymenoxys, Phlox, Cryptantha, Eriogonum and in the Bighorn region, Sphaeromeria capitata. Pseudoroegneria spicata is present at relatively low canopy cover.
Environment:
This uncommon type occurs on windswept, limestone ridge crests and upper slopes in the Tendoy and perhaps Centennial Mountains at 8,000 to 9,000 feet. Adjacent sites with deeper soils are often dominated by Artemisia tridentata ssp. vaseyana and Festuca idahoensis. Cool slopes below these ridges may support Pseudotsuga menziesii or Pinus flexilis forests.
Vegetation:
The dominant graminoids are Pseudoroegneria spicata, Festuca kingii and Carex filifolia. Shrubs are completely absent. A rich assemblage of low forbs exists, including many cushion-forming species such as Cymopterus bipinnatus, Lesquerella alpina, Phlox hoodii, Eritrichium nanum, Oxytropis campestris and Townsendia spp. Forbs have significantly more basal cover than graminoids, especially in the most exposed sites. Mosses and especially lichens are common.
Global Rank: G3? State Rank: S3
Global Rank Comments:
This association is known from two geographic areas in Montana; the low hills and outwash plains along the south slope of the Pryor Mountains and Bighorn Canyon in south-central Montana, and the Tendoy Mountains in south-west Montana. This type also is suspected to correlate with an exposed-site, Pseudoroegneria spicata-dominated type in western Montana, wherein Eriogonum ovalifolium (cushion form) is codominant. This vegetation is naturally found as small landscape patches and may be more extensive than currently known.
Community References
Identifier:
CEGL001666
Author:
99-11-16 / S. V. Cooper, MTNHP
Citations:
Bourgeron and Engelking 1994, Cooper et al. 1999, DeVelice and Lesica 1993, Driscoll et al. 1984
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This information is from the:
Montana Natural Heritage Program
Montana State Library--Natural Resource Information System
1515 East Sixth Ave., Helena, MT 59620-1800
406 444-3989
mtnhp.org
mtnhp@mt.gov
