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Montana Field Guide

Montana Field Guides

Columbia Water-meal - Wolffia columbiana

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. Known from several water bodies in the valleys of western Montana. Additional information on the species is needed within Montana to more precisely determine the species' conservation status.
 
General Description
Columbia Water-meal, a minute floating aquatic perennial, is among the world's smallest flowering plants. The plant body is rootless and thalloid, with no distinction between stem and leaf. The symmetrical, globular, uniformly green thalli are less than 1.5 mm long, smooth and rounded on the back, and floating just below the surface of the water. The plants rarely flower and for the most part reproduce vegetatively by budding. They often grow in large colonies.

Phenology
Rarely if ever observed flowering; vegetative material observed July-September.

Diagnostic Characteristics
Species of Wolffia are distinguished from other genera of small floating aquatics in the duckweed family (Lemna, Spirodella, Wolffiella) by their smaller size, and by being both globose and rootless.Wolffia columbiana is distinguished from other Wolffia by the upper surface of its thallus, which is rounded and smooth (sometimes with minute humps) rather than flattened and/or with sunken brown dots.

Species Range
Present
 


Range Comments
Throughout most of N. America, south to S. America. Sparse.

Summary of Observations Submitted for Montana
Number of Observations: 15

(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
Fresh, shallow water of ponds and sloughs in the valley zone.

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

References
  • Additional ReferencesLegend:   View Online Publication
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    • Bernard, F.A. and J. M. Bernard. 1990. Flower structure and life history of Wolffia australiana (Benth.) den Hartog & van der Plas. Bulletin of the Torrey Botanical Club 117(1):18-26.
    • Burk, C. J., S. D. Lauermann, and A. L. Mesrobian. 1976. The spread of several introduced or recently invading aquatics in western Massachusetts. Rhodora 78(816):767-772.
    • Butler, D. R. 1976. Dendrogeomorphic and biogeographic studies of snow avalanche slopes, Glacier National Park. Proceedings of the Nebraska Academy of Science Affiliated Society 86:71-72.
    • Cassani, J. R. 1981. Feeding Behaviour of Underyearling Hybrids of the Grass Carp, Ctenopharyngodon idella and the bighead, Hypophthalmicthys nobilis on Selected Species of Aquatic Plants. Journal of Fish Biology. 18:127-133.
    • Catling, P. M. and V. R. Brownell. 1987. New and significant vascular plant records for Manitoba. Canadian Field-Naturalist 101(3):437-439.
    • Cody, W.J. 1980. Wolffia columbiana (Lemnaceae), water-meal, new to Manitoba. Canadian Field-Naturalist 94(2):193-194.
    • 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.
    • Kline, L. and B. McCune. 1987. Factors influencing the distribution of Wolffia columbiana and Wolffia punctata (Lemnaceae). Northwest Science 61:41-43.
    • Lesica, P., M. T. Lavin, and P. F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
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Citation for data on this website:
Columbia Water-meal — Wolffia columbiana.  Montana Field Guide.  .  Retrieved on , from