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Montana Field Guide

Montana Field Guides

Spiny-spore Quillwort - Isoetes echinospora
Other Names:  Isoetes tenella

Species of Concern
Native Species

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

Agency Status
MNPS Threat Rank:
C-value: 9

External Links

State Rank Reason (see State Rank above)
Isoetes echinospora is known from 8 occurrences scattered in western Montana. At one occurrence, the species has been observed in 1940, 1967, and 1998 indicating persistence. However, current survey work is needed to document locations, population sizes, and threats.
  • Details on Status Ranking and Review
    Spiny-spore Quillwort (Isoetes echinospora) Conservation Status Review
    Review Date = 09/22/2018
    View State Conservation Rank Criteria
    Range Extent

    ScoreF - 20,000-200,000 sq km (~8,000-80,000 sq mi)

    Area of Occupancy

    ScoreD - 6-25 4-km2 grid cells

    Number of Populations

    ScoreB - 6 - 20

    Number of Occurrences or Percent Area with Good Viability / Ecological Integrity

    ScoreB - Very few (1-3) occurrences with excellent or good viability or ecological integrity

    Environmental Specificity

    ScoreB - Narrow. Specialist or community with key requirements common


    ScoreD - Low

    CommentNo known threats.

General Description
Plants aquatic. Leaves 6–15 cm long with a blunt tip. Sporangia 3–6 mm long. Megaspores 0.4–0.6 mm wide (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Species Range
Montana Range


Range Comments
In MT in Flathead, Lake, Missoula and Ravalli counties; Circumboreal, south to CA, UT, CO, OH, NJ (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 11

(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)

Unconsolidated mud in shallow water of lakes and sloughs; valleys to lower subalpine (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

  • 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.
  • Web Search Engines for Articles on "Spiny-spore Quillwort"
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Citation for data on this website:
Spiny-spore Quillwort — Isoetes echinospora.  Montana Field Guide.  .  Retrieved on , from