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Introduction
According to Ceska and Ceska (2010), this is an "Amphiberingian species, Far East of Asia and British Columbia, Washington and Oregon. Dioecious, population clonal, usually of one sex (female populations prevailing) some populations rarely with hermaphroditic individuals. Terrestrial or semiterrestrial at the margins of lakes and rivers with fluctuating water table, truly aquatic plants rare. Habit is unlike of any other our milfoil. Winter buds inconspicuous, filiform."
Species Information
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expanded illustration for this species.
General: Perennial aquatic or semiterrestrial from a rhizome, stems up to 25 cm tall.
Leaves: Emergent leaves opposite or in whorls of 3, 1-8 mm long, linear or lanceolate in outline, entire or pinnate with 1-3 pairs of segments; submersed leaves in whorls of 3, pinnate, broadly egg-shaped in outline, with 2-4 (7) alternate segments on each side; winter buds 3-7 mm long, threadlike, formed in the leaf axils.
Flowers: Male and female flowers developed on separate plants (plants dioecious) in the axils of the floral bracts; floral bracts similar to the leaves, usually entire, or with a few stubby segments on each side; male flowers with soon deciduous white petals about 3 mm long; stamens 8, deciduous; female flowers inconspicuous, greenish, with four feather-like stigmas.
Fruits: Were not observed in BC.
Notes: Most populations of this species in British Columbia have only female plants; male populations are known from the lower Fraser River valley.
There are ten species of Myriophyllum found in the Pacific Northwest (Ceska and Ceska 2010). View a key to the genus Myriophyllum for this region prepared by Oldriska Ceska and Adolf Ceska (BEN #428).
Habitat / Range
Lake margins and muddy river banks in the lowland zone; rare on Vancouver Island, lower Fraser River valley and SE BC; amphiberingian, in North America known only from BC, WA and OR; China, Primor'ye, Kamchatka, Japan.
