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Howell's Quillwort - Isoetes howellii

Species of Concern
Native Species

Global Rank: G4G5
State Rank: S3
(see State Rank Reason below)

Agency Status
MNPS Threat Rank:
C-value: 8

External Links

State Rank Reason (see State Rank above)
Isoetes howellii is known from about 5 locations in Northwestern Montana. Based on limited information threats appear to be minimal, but survey work to document locations, population sizes, and threats is greatly needed.
  • Details on Status Ranking and Review
    Howell's Quillwort (Isoetes howellii) Conservation Status Review
    Review Date = 09/22/2018
    View State Conservation Rank Criteria
    Range Extent

    ScoreD - 1,000-5,000 sq km (~400-2,000 sq mi)

    Area of Occupancy

    ScoreC - 3-5 4-km2 grid cells

    Number of Populations

    ScoreA - 1 - 5

    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: Semi-aquatic to aquatic. Usually at least 10 cm tall.

LEAVES: Leaves up to 25 mm long and often black near the base (Lesica et al. 2012). Leaves thin and soft, light green, deciduous, and gradually tapering from near the base to a long, very slender tip. The hyaline leaf margins extend for 1-5 cm above the sporangia.

INFLORESCENCE: Sporangia wall streaked to completely brown. Megaspores about 0.3-0.45 mm wide, smooth or tuberculate but not spiny.

Species Range
Montana Range


Range Comments
In MT only known from Flathead, Glacier, Lake and Missoula counties; BC to CA, east to ID and MT (Lesica et al. 2012).

Observations in Montana Natural Heritage Program Database
Number of Observations: 7

(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)

In and around ponds, lakes and sloughs where water recedes; valleys (Lesica et al. 2012).

Plants are often unearthed by waterfowl, and can be found floating (Lesica et al. 2012).

Reproductive Characteristics
Plants collected early in the growing season may have immature spores that cannot be used for identification (Lesica et al. 2012).

  • 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?
    • Garrett, P.A. 1983. Relationships between benthic communities, land use, chemical dynamics, and trophic state in Georgetown Lake. Ph.D. Dissertation. Bozeman, MT: Montana State University. 136 p.
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Citation for data on this website:
Howell's Quillwort — Isoetes howellii.  Montana Field Guide.  .  Retrieved on , from