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Montana Field Guide

Montana Field Guides

Beaked Spikerush - Eleocharis rostellata

Species of Concern
Native Species

Global Rank: G5
State Rank: S3
(see State Rank Reason below)

Agency Status
MNPS Threat Rank: 3
C-value: 9

External Links

State Rank Reason (see State Rank above)
Known from over a dozen extant sites and a few historical locations. Private and state lands host many occurrences that are vital to the viability of the species in the state. The species is vulnerable to hydrologic alteration and development.
  • Details on Status Ranking and Review
    Beaked Spikerush (Eleocharis rostellata) Conservation Status Review
    Review Date = 09/18/2012
    View State Conservation Rank Criteria
    Population Size

    Score1 - Moderate: Generally 10,000-100,000 individuals.

    CommentPopulation estimates are imprecise though appear to be less than 100,000 stems.

    Range Extent

    Score0 - Widespread species within Montana (occurs in 5% or more of the state or generally occurring in 6 or more sub-basins.) as well as outside of Montana.

    Area of Occupancy

    Score1 - Moderate: Generally occurring in 11-25 Subwatersheds (6th Code HUC’s).

    Environmental Specificity

    Score2 - High: Species is restricted to a highly specialized and limited habitat and is typically dependent upon unaltered, high-quality habitat (C Values of 8-10).


    Score1-2 - Minor to Moderate Declines:

    CommentTrends are undocumented, though some declines from habitat loss/alteration seem likely, but it does not appear that the declines have been severe.


    Score1 - Medium: 11-30% of the populations are being negatively impacted or are likely to be impacted by one or more activities or agents, which are expected to result in decreased populations and/or habitat quality and/or quantity.

    CommentHabitat loss/alteration and hydrologic alterations.

    Intrinsic Vulnerability

    Score0-1 - Low to Moderate Vulnerability.

    Raw Conservation Status Score

    Score 6 to 8 total points scored out of a possible 19.

General Description
Caespitose perennial. Stems 10–80 cm, tufted, erect or arching, rooting at the tip and forming new plants. Spikelet 4–10 mm long with few to many flowers. Scales 2–6 mm long, brown to purple with broad hyaline margins, rounded, the lowest empty. Flowers: bristles ca. 6, mostly equaling the achene; stigmas 3. Achenes green-grayish, smooth, obovoid, ca. 2 mm long with a conical tubercle confluent with the body (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Flowering in July, mature fruit in July-August.

Diagnostic Characteristics
The triangular beak is notched all around the base where it attaches to the body of the achene in E. palustris. In E. tenuis the base of the beak is set in a dishlike depression at the top of the achene. The stems of E. rostellata rooting at the tips is diagnostic.

Species Range
Montana Range


Range Comments
BC to NS south through most of U.S. to Mexico (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 47

(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, often alkaline soils, associated with warm springs or fens in the valley and foothills 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

  • Additional ReferencesLegend:   View Online Publication
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    • Fertig, W. and G. Jones. 1992. Plant communities and rare plant species of the Swamp Lake Botanical Area, Clark's Fork Ranger District, Shoshone National Forest. Unpublished report to the Shoshone National Forest. Challenge Cost Share Agreement No. CSA-2-91-14-0001. Wyoming Natural Diversity Database. 113+ pp.
    • Heidel, B. 1994. Potential impact of proposed noxious weed treatment at Bluewater Fish Hatchery (MDFWP) on plant species of special concern. Unpublished report to Gary Shaver, Bluewater Fish Hatchery. Montana Natural Heritage Program, Helena, Montana. 5 pp.
    • Heidel, B. 1994. Sensitive species survey of Bluewater Fish Hatchery of 10 June; memo and documentation provided to Gary Shaver, MDFWP.
    • Lesica, P. 1990. Vegetation and sensitive plant species of wetlands associated with geothermal areas in the greater Yellowstone ecosystem in Montana. Unpublished report on file at the Montana Field Office, The Nature Conservancy, Helena. 9 pp.
    • Lesica, P. 1991. The Rare Vascular Plants of Pine Butte Swamp Preserve. Unpublished Report to the Nature Conservancy. 15 Pp.
    • 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 B.L. Heidel. 1995. Sensitive plant survey in the Tobacco Root Mountains, Madison County, Montana. Unpublished report to the Beaverhead and Deerlodge National Forests. Montana Natural Heritage Program. Helena, MT. 66 pp. plus appendices.
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Citation for data on this website:
Beaked Spikerush — Eleocharis rostellata.  Montana Field Guide.  .  Retrieved on , from