Myriophyllum(redirected from Northern watermilfoil)
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a genus of herbaceous aquatic and marsh plants of the family Haloragidaceae. The leaves are for the most part whorled and usually toothed or pinnatisect; they grow on narrow lobules. The small, plain flowers grow in spikelike inflorescences that rise above the water. The genus consists of approximately 20 species (according to some data, as many as 50), which are distributed over the entire globe. The USSR has five species, the best-known of which are M. spicatum and the myriad leaf. Some species are grown in aquariums.