Submerged water plants are those aquatic plants that are able to grow entirely under the water, although at times the upper part of the plant may be above the surface. While some pond owners may think that these plants are a nuisance, in reality they add much to the aquatic environment if they are properly controlled. Submerged flowering water plants provide food for waterfowl, hiding places for fish and add oxygen to the water.
Hydrilla verticillata is native to Asia and was brought to the United States in the early 1960s, according to the University of Florida. This extremely hardy plant spreads rapidly and quickly became invasive in many areas. Hydrilla verticillata attaches itself to the bottom of freshwater environments. The plant has long stems and develops branches when the stem gets close to the surface of the water. The small, white flowers bloom on the ends of the stems and float on the surface of the water.
Hydrilla verticillata often overtakes and crowds out desirable, native aquatic plants. It also clogs canals and waterways and can interfere with swimming and other water activities.
Naiads (Najas spp.) are a large group of submerged flowering water plants, five of which are native to the United States. There are about 40 different species of Najas worldwide, according to the University of Florida, including Najas guadalupensis, or Southern naiad. Southern naiad is found all throughout the United States and even into parts of Canada. These plants like freshwater, and can be found in bodies of water ranging from clear mountain springs to stagnant bogs.
Naiads have long stems that are lined with several branches. The leaves are thin and about an inch long with serrated edges. They are a dark, purplish-green in color. The flowers of the Najas species are quite tiny, white and very inconspicuous.
Myriophyllum spicatum, or Eurasian water-milfoil, is a perennial plant that roots itself to the sediment but flowers above the water. It can reach up to 20 feet in height. Individual stems grow up to 9 feet long. The leaves are feathery and are about 2 inches long. The flowers are very small and reddish-brown or pink in color.
This plant is so invasive that it can stop boat traffic and fill a large lake completely. Small pieces of Eurasian water-milfoil can break off, float away and easily take root. It can grow in slow or fast-moving water and has even been found in slightly salty water. This plant is also tolerant of warm or cold water, growing well in both Canada and the far south.