Myriophyllum spicatum L.
Eurasian water-milfoil (Eurasian watermilfoil)
Haloragaceae (Water Milfoil family)

Introduction to Vascular Plants


© Jamie Fenneman     (Photo ID #14152)


E-Flora BC Static Map

Distribution of Myriophyllum spicatum
Click here to view the full interactive map and legend


According to Ceska and Ceska (2010), this species is "Introduced and invasive. North American invasive populations are considered to be of a hybrid origin (M. spicatum x M. sibiricum) by Moody & Les (2002, 2007). Stem drying reddish. No winter buds."

Species Information

Perennial aquatic from a rhizome, stems usually branched, to 250 cm long, reddish-brown, pinkish-tawny in drying.
In whorls of 3 to 5 mostly 1 cm apart or more on stem, those in the middle whorls usually less than 2.5 cm long, simply pinnate with 12 or more segments on each side of rachis; segments rarely to 1.5 cm long, in a regular, feather-like arrangement, about 1-2.5 mm apart; winter buds absent.
Spikes to about 15 cm long, emergent erect; flowers usually in whorls of 4 in the axils of bracts; all but the lowest bracts essentially entire and shorter than the flowers and fruits, the lowest comb-like to sharply toothed and commonly exceeding the flowers; flowers progressing from basal whorls of pistillate flowers through 1 perfect flower to the upper whorl of male flowers with reddish, soon deciduous petals about 3 mm long; stamens 8.
Mericarps, 4, nearly round, with tiny warts on the dorsal ridges.
This species was introduced to British Columbia in the early 1970's and has become a serious aquatic weed. In Hitchcock et al. (1961) plants of this species would key out as "Myriophyllum spicatum var. exalbescens."

SourceThe Illustrated Flora of British Columbia


If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.


Ecological Framework for Myriophyllum spicatum

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)
800 390 1295
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]
8 8 8
Modal Nutrient Regime
# of field plots
 species was recorded in:
Modal BEC Zone Class

All BEC Zones (# of stations/zone) species was recorded in

ICH(1), IDF(6), SBPS(8), SBS(23)

Habitat and Range

Lakes, sloughs, channels and duck ponds in the lowland, steppe and montane zones; locally common, scattered throughout S BC; E to ON and PQ and S through the US; introduced from Eurasia.

SourceThe Illustrated Flora of British Columbia


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