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Montana Field Guide

Montana Field Guides

Three-flowered Rush - Juncus triglumis var. triglumis

Status Under Review
Native Species

Global Rank: G5T5
State Rank: SU

Agency Status
MNPS Threat Rank:
C-value: 8

External Links

General Description
Fibrous-rooted, caespitose. Stems erect, 3–20 cm. Leaves basal; blades terete, septate, <1 mm wide; auricles minute, rounded. Inflorescence a small head with 2 to 4 sessile flowers subtended by 2 scarious bracts shorter than the inflorescence. Flowers: prophylls absent; tepals brown to whitish, 3–5 mm long, acute; stamens 6. Capsules 3–6 mm long, rounded, shorter or longer than the tepals; seeds with appendages as long as the body (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Mature fruit in August.

Diagnostic Characteristics
Of the small, high alpine rushes, Juncus castaneus has larger flowers, J. biglumis has only 2 flowers and capsules that are indented on top, and J. albescens has bracts that are as long as the flower head, and mature capsules that are 3-5 mm long; ca. as long as the light brown tepals. A hand lens or microscope and technical key are needed for positive identification.

Species Range

Range Comments
Circumpolar south to UT and CO (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 5

(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)

Wet, non-calcareous soil of seeps and fens in the alpine zone.

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Citation for data on this website:
Three-flowered Rush — Juncus triglumis var. triglumis.  Montana Field Guide.  .  Retrieved on , from