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Montana Field Guide

Montana Field Guides

Guadalupe Water-nymph - Najas guadalupensis

Species of Concern

Global Rank: G5
State Rank: S2S3
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank:
C-value: 7

External Links






State Rank Reason (see State Rank above)
Rare. Currently documented from a few fresh water sites in the western and central portions of the state. Species is poorly documented in Montana and additional information on population levels, trends and threats is needed.
  • Details on Status Ranking and Review
    Guadalupe Water-nymph (Najas guadalupensis) Conservation Status Review
    Review Date = 06/10/2012
    View State Conservation Rank Criteria
    Population Size

    Score1-2 - Small to Moderate. Population size is imprecisely known but is believed to be >2,000 individuals and <100,000 individuals.

    Range Extent

    Score1 - Peripheral, Disjunct or Sporadic Distribution in MT: Widespread species that is peripheral, disjunct or sporadically distributed within MT such that it occurs in <5% of the state (<7,500 sq. miles or the combined area of Beaverhead and Ravalli Counties) or is restricted to 4-5 sub-basins.

    Area of Occupancy

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

    Environmental Specificity

    Score1-2 - Moderate to High.

    Trends

    Score0-3 - Population trends are unknown.

    CommentTrends are unknown.

    Threats

    Score0-2 - Low to High Threat Levels.

    CommentPotential threats to the species' viability are unknown/undocumented.

    Intrinsic Vulnerability

    Score1-2 - Moderate to High Vulnerability.

    Raw Conservation Status Score

    Score 6 to 14 total points scored out of a possible 19.

 
General Description
Guadalupe Water-nymph is a submerged aquatic annual with slender, branching stems up to about 7 dm long. The opposite, ribbon-like leaves, usually with additional leaves in their axils, are 0.5-2 cm long and have minutely toothed margins and enlarged bases. Tiny unisexual flowers, both male and female on the same plant, are borne singly, without stalks, in the axils of leaves. The male flowers have a single stamen enclosed in a translucent bract which is surrounded by a firmer bract, and the female flowers consist of a single naked pistil. The fruits are single seeded with a thin, papery covering. The long tapered seeds are round in cross-section and are dull and coarsely pitted with 10-20 rows of pits across the middle.

Phenology
Flowering in July, with mature fruit in August.

Diagnostic Characteristics
Distinguished from other genera of submerged aquatics in Montana by its opposite ribbon-like leaves with expanded bases, usually with secondary leaves in their axils, and also by its solitary, axillary, unisexual flowers. Distinguished from the more common Najas flexilis by having shorter stems, shorter leaves with short tapering tips rather than long tapering tips, and seeds which are dull and coarsely pitted rather than shiny with minute pits.

Species Range
Present
 


Range Comments
OR to CA, widely scattered to the Atlantic coast; Mexico to S. America, West Indies. Peripheral.

Summary of Observations Submitted for Montana
Number of Observations: 6

(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
Submerged in shallow, fresh waters of oxbow sloughs, ponds, and reservoirs in valleys.

Ecological Systems Associated with this Species
  • Commonly Associated with these Ecological Systems
    Wetland and Riparian Systems

References
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Citation for data on this website:
Guadalupe Water-nymph — Najas guadalupensis.  Montana Field Guide.  .  Retrieved on , from