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Montana Field Guide

Montana Field Guides

Pepperwort - Marsilea oligospora

Species of Concern
Native Species

Global Rank: G5
State Rank: S2
(see State Rank Reason below)

Agency Status
MNPS Threat Rank:

External Links

State Rank Reason (see State Rank above)
Marsilea oligospora has relatively recently been segregated from Marsilea vestita (FNA 1993). It is quite common around Ninepipes National Wildlife Refuge, but has not been documented elsewhere in Montana. Observation data is greatly needed to further assess its distribution and viability in Montana.
  • Details on Status Ranking and Review
    Pepperwort (Marsilea oligospora) Conservation Status Review
    Review Date = 09/01/2017
    View State Conservation Rank Criteria
    Range Extent

    ScoreA - <100 sq km (< ~40 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

    ScoreC - Few (4-12) occurrences with excellent or good viability or ecological integrity

    Environmental Specificity

    ScoreB - Narrow. Specialist or community with key requirements common


    ScoreB - High

    CommentThreat category includes: Noxious weeds (potential) and hydrologic alterations (potential).

General Description
Leaf petioles 3–6 cm long. Pinnae 6–15 mm long, pilose. Sporocarps nodding, 5–6 mm long, long-hairy but glabrous with age; lower tooth ca. 0.5 mm; upper tooth blunt, smaller, or absent (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Species Range

Range Comments
Ranging from WA to CA, extending east to MT, WYand UT.

Observations in Montana Natural Heritage Program Database
Number of Observations: 1

(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)

Shallow water; valleys; collected in Lake Co. and the Blackfoot River Valley (Lesica 2012.

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Citation for data on this website:
Pepperwort — Marsilea oligospora.  Montana Field Guide.  .  Retrieved on , from