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

Wolffia borealis (Engelm. ex Hegelm.) Landolt ex Landolt & Wildi
northern water-meal (northern watermeal)
Lemnaceae

Introduction to Vascular Plants
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Distribution of Wolffia borealis
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Introduction

Wollfia borealis is a tiny perennial, clonal aquatic plant that lacks roots and definite leaves or stems. It is found in North America across the more northern US states (CA, CO, CT, IA, ID, IL, IN, KS, KY, MA, MD, MI, MN, MO, MT, NC, NE, NH, NJ, NY, OH, OR, PA, SD, TN, UT, VA, VT, WA, WI) and is reported in Canada in BC, Alberta, Ontario and Quebec (USDA 2010). It is found in lakes, ponds and ditches, and has been reported in BC from several locations in the lower Fraser Valley. In his essay on the rare plants of the Fraser Valley, Lomer (2011) says:

"Rarely seen in the Fraser Valley (Ceska & Ceska 1980), this miniscule aquatic plant looks like nothing more than green scum. It is proving to be more common than first thought, but is rather sporadic from year to year. New sites from Cultus Lake, Vancouver (UBC: Lomer 6754) and Cheam wetlands suggest it occurs from one end of the Fraser Valley to the other, especially in the central valley. It is not endangered as long as there are sloughs and Typha ponds and lakeshores. Easily overlooked, but uncommon nevertheless. It often grows with Lemna and Spirodella and is presumably spread by ducks so it can show up just about anywhere that ducks feed and where water is adequate. It can have explosive exponential growth late in the season, but is so tiny that only several square meters are covered in most instances."

Species Information

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General:
Fronds annual, free-floating, elliptic to egg-shaped, nearly twice as long as wide, 0.5-1.2 mm long, dark green, upper surface flat with 15 to 100 stomates, usually in unequal pairs, rootless, with a pouch at the basal end from which young plants arise.
Flowers:
Two, together on the upper surface, 1 female, 1 male; stamen 1; pistil 1.
Fruits:
Utricles (inflated fruits), globe-shaped; seeds 1, smooth.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Ponds, lakes and slow-moving streams in the lowland and montane zones; rare in the lower Fraser Valley and SE BC (Creston); disjunct in ON and PQ and S to CT, NC, TN, MO, KS, CO, UT and CA.

Source: The Illustrated Flora of British Columbia

Climate

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

Wolffia punctata auct. non Griseb.

Taxonomic and Nomenclatural Links

Additional Photo Sources

Related Databases

Species References

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

Lomer, Frank. 2010. Personal communication. E-mail.

USDA. 2010. Plant profile for Wolffia borealis. United States Department of Agriculture. Available Online.

General References