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

Myriophyllum farwellii Morong
Farwell's water-milfoil
Haloragaceae (Water Milfoil family)

Introduction to Vascular Plants
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Distribution of Myriophyllum farwellii
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Ceska and Ceska (2010) provide the following note about this species: "North American species distributed in eastern North America; in the Pacific Northwest known from Alaska & British Columbia. Easily overlooked since it grows relatively deep at the bottom of dystrophic lakes. Usually copiously fruiting at the base of the stem leaves. Winter buds absent."

Species Information

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Perennial submersed aquatic from a rhizome; stems slim, 1-2 mm wide, dark reddish-green, forming dense stands of more or less uniform height, 30-70 cm tall.
Partly in whorls of 3 to 6, and partly scattered alternate; pinnate, the divisions finely capillary in 5 to 7 opposite or subopposite pairs, with minute black glands in the axils; winter buds absent.
Unisexual, solitary in the axils of the leaves; petals 4, purplish, oblong; stamens 4, anthers minute, abortive; styles 4, short.
Mericarps, 4, angular, 2 mm long, 1.5 to 2 mm wide, with tiny warts on the dorsal ridge.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Lakes, ponds and slough bottoms in the lowland and lower montane zones; infrequent, scattered throughout S BC; E to MB and NS, and S to MI and MN.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Myriophyllum farwellii

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)
Slope Gradient (%)
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
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: CDF(1)


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 cool temperate & cool mesothermal.

Taxonomic and Nomenclatural Links

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Species References

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

General References