AppearanceEurasian watermilfoil has slender stems up to 250 centimetres long. The submerged leaves are borne in pinnate whorls of four, with numerous thread-like leaflets roughly 4–13 mm long. Plants are monoecious with flowers produced in the leaf axils on a spike 5–15 cm long held vertically above the water surface, each flower is inconspicuous, orange-red, 4–6 mm long. Eurasian water milfoil has 12- 21 pairs of leaflets while northern watermilfoil ''M. sibiricum'' only has 5–9 pairs. The two can hybridize and the resulting hybrid plants can cause taxonomic confusion as leaf characters are intermediate and can overlap with parent species.
Distribution''Myriophyllum spicatum'' is found in disperse regions of North America, Europe, Asia, Australia, and Africa.
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