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

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

Introduction to Vascular Plants

© Jamie Fenneman  Email the photographer   (Photo ID #14152)

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Distribution of Myriophyllum spicatum
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Introduction

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

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General:
Perennial aquatic from a rhizome, stems usually branched, to 250 cm long, reddish-brown, pinkish-tawny in drying.
Leaves:
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.
Flowers:
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.
Fruits:
Mericarps, 4, nearly round, with tiny warts on the dorsal ridges.
Notes:
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."

Source: The Illustrated Flora of British Columbia

Habitat / 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.

Source: The Illustrated Flora of British Columbia

Ecology

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

Minimum

Average

Maximum

Elevation (metres) 390 800 1295
Slope Gradient (%) 0 0 0
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
0
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
8 8 8
Modal Nutrient Regime
Class
C
Number of field plots
 species was recorded in:
38
Modal BEC Zone Class
SBS
All BEC Zones (# of stations/zone) species was recorded in: ICH(1), IDF(6), SBPS(8), SBS(23)

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.

Taxonomic and Nomenclatural Links

Additional Photo Sources

Related Databases

Species References

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

General References