E-Flora BC: Electronic Atlas of the Flora of British Columbia

Wolffia columbiana Karst.
Columbian water-meal (Columbian watermeal)

Introduction to Vascular Plants

© Jamie Fenneman  Email the photographer   (Photo ID #5998)

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Distribution of Wolffia columbiana
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This is a tiny floating perennial aquatic plant that lacks roots and definite leaves or stems. It is clonal and occurs in thick populations that often appear as scum on the surface of still waters, such as ditches, ponds, and lake edges. It is distinctly smaller than the more familiar duckweed (Lemna minor). View a comparative photo. In North America, Columbian water-meal is found across the US (though absent from AZ, NM, UT, CO, ID, WY, WA) and Canada (AB, BC, MB, NB, ON, QC, SK) (USDA 2010). In BC, it is so far reported only from southwestern Vancouver Island, from Swan Lake. However, it might be overlooked and should be looked for, for example, in the Lower Mainland.

Species Information

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Fronds annual, free-floating, globe-shaped, about as long as wide, 0.8-1.3 mm long, transparent green, round except for flat center with 1 to 10 (30) stomates, usually in unequal pairs, rootless, with a pouch at the basal end from which young plants arise.
Two, together on the upper surface, 1 female, 1 male; stamen 1; pistil 1.
Utricles (inflated fruits), globe-shaped; seeds 1, smooth. vol6_8

Source: The Illustrated Flora of British Columbia

Habitat / Range

Ponds and lakes in the lowland zone; rare in SW BC, known only from the Saanich Peninsula; E to PQ and S to MA, PA, FL, MS, TX, CO and CA; S. America.

Source: The Illustrated Flora of British Columbia


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Synonyms and Alternate Names

Bruniera columbiana (Karst.) Nieuwl.

Taxonomic and Nomenclatural Links

Additional Photo Sources

Species References

Hickman, James C. 1993. The Jepson Manual of the Higher Plants of California. University of California Press, Los Angeles.

Washington Department of Natural Resources. 2005. Wolffia columbiana page. On-line Field Guide to Selected Rare Plants of Washington. Washington Department of Natural Resources, Washington Natural Heritage Program and the U.S.D.I. Bureau of Land Management.

General References