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Montana Field Guide

Montana Field Guides

Scalepod - Idahoa scapigera

Species of Concern

Global Rank: G5
State Rank: S1S2
* (see State Rank Reason below)

Agency Status
USFWS:
USFS: SENSITIVE
BLM:
MNPS Threat Rank: 1
C-value:

External Links






State Rank Reason (see State Rank above)
Rare and peripheral in Montana. Currently known from approximately a half-dozen sites in western Montana, mostly along the lower slopes of the Bitterroot Mountains. Populations are highly susceptible to negative impacts from invasive weeds, primarily spotted knapweed and cheatgrass. Data on population trends are lacking, though levels likely fluctuate widely from year to year.
  • Details on Status Ranking and Review
    Scalepod (Idahoa scapigera) Conservation Status Review
    Review Date = 05/30/2012
    View State Conservation Rank Criteria
    Population Size

    Score2-3 - Very Small to Small: Population size is imprecisely known but is believed to be <10,000 individuals.

    Range Extent

    Score2 - Regional or State Endemic or Small Montana Range: Generally restricted to an area <100,000 sq. miles (equivalent to 2/3 the size of Montana or less) or Montana contributes 50% or more of the species’ range or populations OR limited to 2-3 Sub-basins in Montana.

    CommentPeripheral in western Montana.

    Area of Occupancy

    Score2 - Low: Generally occurring in 4-10 Subwatersheds (6th Code HUC’s).

    Environmental Specificity

    Score1-2 - Moderate to High.

    Trends

    ScoreNA - Rank factor not assessed.

    CommentTrends are unknown, though may be declining due to impacts to habitat quality, particularly from invasive species.

    Threats

    Score2-3 - High to Very High.

    CommentInvasive species such as cheatgrass and spotted knapweed are a primary threat.

    Intrinsic Vulnerability

    Score1-2 - Moderate to High Vulnerability.

    Raw Conservation Status Score

    Score 10 to 14 total points scored out of a possible 16 (Rarity factors and threats only).

 
General Description
Scalepod is a small, glabrous annual with many leafless stems that are up to 10 cm high. The numerous basal leaves have a long, slender petiole and narrowly elliptic blades that are 5-15 mm long with entire margins or two shallow lobes near the base. Each stem bears a single white flower at the tip. Each flower has 4 red to purple, separate sepals that are ca. 2 mm long, 4 separate petals of the same length, and 4 long and 2 short stamens. The flowers quickly form flattened, nearly circular fruits that are 6-12 mm in diameter with 6-12 wing-margined seeds inside.

Phenology
Flowering in March-April.

Diagnostic Characteristics
Species of Draba and Subularia have more than one flower (or fruit) per stem.

Species Range
Present
 


Range Comments
WA to CA, east to ID and w. MT. Peripheral.

Summary of Observations Submitted for Montana
Number of Observations: 21

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Habitat
Vernally moist, open soil on rock ledges in the lower montane zone.

References
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Citation for data on this website:
Scalepod — Idahoa scapigera.  Montana Field Guide.  .  Retrieved on , from