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

Myriophyllum verticillatum L.
verticillate water-milfoil (whorl-leaf watermilfoil)
Haloragaceae (Water Milfoil family)

Introduction to Vascular Plants

© Bryan Kelly-McArthur  Email the photographer   (Photo ID #75004)

E-Flora BC Static Map
Distribution of Myriophyllum verticillatum
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Ceska and Ceska (2010) say the following about this species: "Circumpolar species. Occurs sporadically throughout Canada, Pacific Northwest, and NE parts of the USA. Stems and leaves green, leaves often with "myriophylloid glands" at the base of the lowermost segments. Winter buds frequent, clavate."

Species Information

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Perennial aquatic from creeping rhizome, wholly submersed, or with the spike and upper leaves sometimes emersed; stems simple or with a few elongate branches up to 250 cm long.
In whorls of 4 or 5; submersed leaves to 45 mm long, with 9 to 13 opposite or alternate pairs of flacid capillary segments to 28 mm long; emersed leaves and bracts smaller and with coarser divisions or merely comb-like pinnate; winter buds well developed at the end of the growing season, 1-4 cm long, club-shaped, broadest at the top.
In whorls of 4-6, perfect or the lower ones female and the upper male; bracteoles minute, palmately 7-lobed, about 0.5 mm long; petals spoon-shaped or rudimentary in female flowers, obtuse, about 2.5 mm long; stamens 8, about 2 mm long.
Mericarps nearly round, 2-2.5 mm long, glabrous or more or less with tiny warts, rounded on back.
Mistakenly treated as a synonym of "Myriophyllum spicatum var. spicatum."in Hitchcock et al. (1961).

Source: The Illustrated Flora of British Columbia

Habitat / Range

Lakes and sloughs of the lowland to montane zones; frequent throughout BC; circumpolar, N to AK and YT, E to NF, and S to FL, MN, UT, and CA; Eurasia.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Myriophyllum verticillatum

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres) 985 1080 1175
Slope Gradient (%) 0 0 0
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
7 7 8
Modal Nutrient Regime
Number of field plots
 species was recorded in:
Modal BEC Zone Class
All BEC Zones (# of stations/zone) species was recorded in: CWH(1), IDF(5)


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

Myriophyllum scabratum Michx.
Myriophyllum verticillatum var. cheneyi Fassett
Myriophyllum verticillatum var. intermedium W.D.J. Koch
Myriophyllum verticillatum var. pectinatum Wallr.
Myriophyllum verticillatum var. pinnatifidum Wallr.
Potamogeton pinnatum Walter

Taxonomic and Nomenclatural Links

Additional Photo Sources

Species References

Ceska, Oldriska and Adolf Ceska. 2010. Genus Myriophyllum (Haloragaceae) in the Pacific Northwest. Botanical Electronic News #428. Available online.

General References