Guadalupe Water-nymph - Najas guadalupensis
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
Score1-2 - Small to Moderate. Population size is imprecisely known but is believed to be >2,000 individuals and <100,000 individuals.
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).
Score1-2 - Moderate to High.
Score0-3 - Population trends are unknown.
CommentTrends are unknown.
Score0-2 - Low to High Threat Levels.
CommentPotential threats to the species' viability are unknown/undocumented.
Score1-2 - Moderate to High Vulnerability.
Raw Conservation Status Score
6 to 14 total points scored out of a possible 19.
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.
Flowering in July, with mature fruit in August.
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.
OR to CA, widely scattered to the Atlantic coast; Mexico to S. America, West Indies. Peripheral.
Observations in Montana Natural Heritage Program Database
Number of Observations:
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Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
Submerged in shallow, fresh waters of oxbow sloughs, ponds, and reservoirs in valleys.
Ecological Systems Associated with this Species
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
- Fassett, N. C. 1985. (3rd ed.) A Manual of Aquatic Plants, with Revision Appendix by E. C. Ogden. University of Wisconsin Press, Madison. 405 pp.
- Haynes, R.R. 1979. Revision of North and Central American Najas (Najadaceae). Sida 8:34-56.
- Lesica, P., M. T. Lavin, and P. F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.