Myriophyllum sibiricum Komarov: Northern milfoil. Haloragaceae (watermilfoil family). Native perennial. A submersed plant, growing to 10 - 14 ft (3 - 4 m); rhizomes root in sediment in still or moving, preferably clear, water. Unlike M. spicatum, it does not usually form a canopy at the surface. The stem is stouter than in M. spicatum, and the whorls of 3 to 4 leaves are spaced wider apart on the stem. The feather-like leaves are made of up thread-like divisions arrayed flat along a central midrib; leaves are up to 1.6 in (4 cm) long. The number of leaflet divisions is usually less than 14 per side on an individual leaf, fewer than in M. spicatum. These divisions are longer at the leaf base and shorter at the tip so the overall outline of a flattened leaf is pointed and lance-shaped. The flower stalk emerges above water. Plants can reproduce via rooted stem fragments and by winter buds, which are dense clusters of leaves formed at branch tips. Provides worthwhile habitat and seldom reaches nuisance levels.