• Ponds add to the landscape.Goodshoot/Goodshoot/Getty Images
  
  Pond plants play a vital role in the health of your pond. Besides being ornamental, pond plants improve water quality by filtering out harmful elements from the water and adding oxygen. Mature pond plants create shelters, from the sun and predators, for fish and other aquatic life. Some pond plants even serve as a handy snack for varieties of pond fish. A healthy pond boasts several types of mature pond plants.
  
  

Submerged Plants

• Some plants grow completely under water.piranha image by Lucid_Exposure from Fotolia.com
  
  Submerged plants are those that grow underwater. These plants generally have thin, narrow leaves and survive with little sunlight, according to the University of California. In shallow water, these plants may have some growth above water, such as flowers or leaves, but can survive completely submerged. Parrot's feather (Myriophyllum aquaticum) and elodea (Elodea canadensis) are two examples of submerged pond plants. Parrot's feather is pale green underwater, darkening with more exposure to sunlight. This plant grows about 12 inches tall and is hardy from United State Department of Hardiness Zones 5 through 11. Elodea is deep green with small rubbery leaves. This plant can grow 4 feet tall when mature. Like many pond plants, elodea multiplies rapidly and is considered invasive. Take care when thinning to dispose of this, and all aquatic plants, where it won't end up in natural water sources.
  
  

Floating Plants

• Water lily is a graceful, elegant plant.water lily image by Tomasz Pawlowski from Fotolia.com
  
  Some of the most popular water plants, floating plants often grow large, exotic flowers. These plants either float freely on the surface of the water with dangling roots, or long roots anchor them to the bottom of the pond while most of the plant floats on the water's surface. Water lilies (Nymphaea odorata) have thick, floating leaves that are almost round with triangle-shaped notch cut out of one curve. These leaves are attached to long flexible stems which grow from rhizomes buried under the pond floor. Large fragrant flowers bloom on mature plants from June to September according to Washington State Department of Ecology. Frog-bit is an example of a free floating pond plant. Green, spongy leaves float on the top of the water, leaving the roots to dangle in the water. This plant produces a single white flower in the summer. Frog-bit is considered invasive in parts of the United States and as the plants mature, they should be thinned and disposed of with care.
  
  

Marginal Plants

• Cattails grow in clumps.cattails image by Pix by Marti from Fotolia.com
  
  Marginal plants grow on the edges of the pond where their roots are submerged and leaves are free of the water. These plants thrive in boggy, or consistently wet growing conditions. Louisiana Irises (Iridaceae) and cattails (Typha) are examples of marginal plants. Blooming in vibrant colors, Louisiana irises brighten up any garden pond. Long, thin leaves grow 30 inches tall in USDA Hardiness zones 5 through 10, according to Floridata. These plants bloom in early spring in shades of white, purple, yellow and red in partial to fun sun. Cattails grow from rhizomes and form dense clumps of tall green, grass-like foliage. Mature plants can grow up to 10 feet tall. The flowers are long brown cylinders with no recognizable petals. Cattails provide shelter for fish, amphibians and birds.