Variable-leaf watermilfoil is a perennial plant that has reddish stems that can be branched and two leaf forms. All leaves are in whorls of four to six. The stem sticks out of the water 3 to 6 inches with bright green stiff serrated leaves that are 3/8 to 1 1/4 inches long and 1/10 to 1/2 inches wide. The submerged leaves are feather-like and flaccid, 3/4 to 2 1/2 inches long and 3/4 to 1 1/2 inches wide with 8 to 18 thin segments. The flowers are small 1/16 to 1/8 of an inch long with 4 reddish oval petals in whorls of 4 to 6. Variable-leaf watermilfoil can reproduce by seeds or fragmentation and is an aggressive invader. Because of its tremendous growth rate variable-leaf watermilfoil can completely takeover shallow ponds.
Submerged portions of all aquatic plants provide habitats for many micro and macro invertebrates. These invertebrates in turn are used as food by fish and other wildlife species (e.g. amphibians, reptiles, ducks, etc.). After aquatic plants die, their decomposition by bacteria and fungi provides food (called “detritus”) for many aquatic invertebrates. Variable-leaf watermilfoil seeds and foliage are somewhat consumed by ducks.