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Montana Field Guide

Montana Field Guides

Mat Buckwheat - Eriogonum caespitosum

Species of Concern
Native Species

Global Rank: G5
State Rank: S2S3
(see State Rank Reason below)

Agency Status
MNPS Threat Rank: 3

External Links

State Rank Reason (see State Rank above)
Rare in Montana, where it is has been documented from a few sites from Beaverhead County. Trends are unknown, though the potential for negative impacts to known populations appears to be low.
General Description
Mat Buckwheat is a low, perennial herb or subshrub that forms cushions up to 5 cm high. The alternate, oblong leaves are 10-15 mm long, including the petiole, have entire, downturned margins, and persist on the stem after withering. The foliage is covered with long, gray hairs. The numerous flowers are borne in crowded, globose inflorescences atop leafless stalks that are 3-8 cm high. Flowers arise from a solitary, cup-shaped involucre with 6-7 reflexed lobes. Each flower has 6 yellow and rose, petal-like perianth segment that are 3-5 mm long. The perianth segments are united below and taper to a hairy woolly base.

Flowering in June.

Diagnostic Characteristics
The tapered, stalk-like perianth and the solitary involucre distinguish this species from other mat-forming Erigonum.

Species Range

Range Comments
Southeast OR to CA, east to central ID, MT, WY, and CO.

Observations in Montana Natural Heritage Program Database
Number of Observations: 90

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



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

Dry, stony limestone sagebrush steppe.

Ecological Systems Associated with this Species

  • Additional ReferencesLegend:   View Online Publication
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    • Lesica, P. and J. Vanderhorst. 1995. Sensitive plant survey of the Sage Creek area, Beaverhead County, Montana. Unpublished report to the Bureau of Land Management. Montana Natural Heritage Program. 36 pp. plus appendices.
    • Lesica, P., M. T. Lavin, and P. F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Vanderhorst, J.P. and P. Lesica. 1994. Sensitive plant survey in the Tendoy Mountains, Beaverhead County, Montana. Unpublished report to the Bureau of Land Management, Butte District. Montana Natural Heritage Program, Helena, MT. 59 pp. plus appendices.
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Citation for data on this website:
Mat Buckwheat — Eriogonum caespitosum.  Montana Field Guide.  .  Retrieved on , from