Search Field Guide
Advanced Search
MT Gov Logo
Montana Field Guide

Montana Field Guides

Coville's Rush - Juncus covillei

Species of Concern
Native Species

Global Rank: G5
State Rank: S2S3
(see State Rank Reason below)
State Threat Score: No Known Threats
C-value: 4

Agency Status


External Links

State Rank Reason (see State Rank above)
Rare and peripheral in Montana. Currently known from approximately a half-dozen widely scattered wetland/riparian sites in the mountainous portion of the state.
General Description
Rhizomatous. Stems erect, compressed, 6–20 cm, sometimes clumped. Leaves basal and cauline; blades flat, 1–2 mm wide; auricles acute or absent. Inflorescence congested with 3 to 7 sessile flowers in each of 1 to 3 clusters; main bract shorter or longer than the inflorescence. Flowers: prophylls absent; tepals brown to purplish with a green midstripe, 3–4 mm long, acute; stamens 6. Capsules 3–5 mm long, truncate on top; seeds without appendages (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

We have varieties covillei and obtusatus C.L. Hitchc.

Fruits reach maturity from late August-September

Diagnostic Characteristics
Juncus is a large and difficult genus to distinguish, so a technical key should be consulted. Mature fruit is necessary for positive determination. The combination of flowers subtended by a single bract, flattened leaves, and 7-flowered heads separate J. covillei from most other rhizomatous rushes. The tepals of var obtusatus are pale brown, and the inner ones have pointed tips. In contrast, the tepals of variety covillei are dark brown, and the inner tepals have rounded tips.

Species Range
Montana Range Range Descriptions


Range Comments
BC to CA, ID and MT (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 13

(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)

Variety covillei is typically found in moist, gravelly or sandy soil along major water courses in the valley zone. In contrast, variety obtusatus is found in moist to wet, often seepy soil of slopes and meadows in the montane and subalpine zones.
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

Ecological Systems Associated with this Species

Threats or Limiting Factors
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).

  • Literature Cited AboveLegend:   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 ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • 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.
    • Vanderhorst, J.P. 1994. Sensitive plant surveys in the Gallatin National Forest, Montana. Unpublished report to the Gallatin National Forest. Montana Natural Heritage Program, Helena, MT. 54 pp.
    • Vanderhorst, J.P. 1994. Survey for sensitive plant species on Doherty Mountain, Jefferson County. Unpublished report to the Butte District, Bureau of Land Management. Montana Natural Heritage Program, Helena, MT. 5 pp. plus appendices.
  • Web Search Engines for Articles on "Coville's Rush"
Login Logout
Citation for data on this website:
Coville's Rush — Juncus covillei.  Montana Field Guide.  .  Retrieved on , from