The variety of plants that can live in and around fresh water all over the world is quite extensive. Plants that can survive and thrive in wet, marshy areas or that live in and on top of water are called aquatic or hydrophytic plants (hydrophytes). Some aquatic plants grow completely beneath the surface, and some grow partially beneath and partially above. Aquatic plants can grow in the wild, or in aquariums and man-made ponds.
Requirements
In addition to the hydrogen, oxygen and carbon found in the water and air that they live in, aquatic plants also need the nutrients that are found in the rich soil that is in and around freshwater ecosystems. These nutrients include a large range of macro-elements such as magnesium, nitrogen, phosphorous and potassium. Decomposing organic matter that surrounds freshwater areas adds to these nutrients.
Types
There are three major types of hydrophytic plants. There are plants that are rooted in the mud. These plants can have leaves that are either completely submerged in the water or that extend out of the water. The second type is floating plants whose roots do not attach to the bottom but float free in the water. The majority of these plants' leaves or flowers are above the surface. The third type is plants that are rooted in the mud along the edge of the water; they are somewhere between being an aquatic plant and a terrestrial plant.
1) Submerged Aquatic Plants
- Anacharis
Submerged aquatic plants help to produce oxygen in the water, and are very beneficial to aquatic life. For this reason, submerged plants are very popular with aquarium owners. There are many species of submerged aquatic plants, including Anacharis, Cabomba, Hornwort, Red Ludwigia and Vallisneria
Vallisneria spiralis
Amazon sword 
Riccia fluitans2) Floating Aquatic Plants
- Water Lettuce
Floating aquatic plants also help to oxygenate and filter the water. Floating plants are a favorite of those who create their own backyard ponds and Koi ponds. Some examples of floating plants are Frogbit, Large Leaf Sensitive Plant, Parrot's Feather, Red Stemmed Parrot's Feather, Water Hyacinth, Jumbo Water Hyacinth and Water Lettuce. The most popular versions of floating plants for the backyard Koi pond, mostly because of their beautiful blooms, are the Water Lily and the Lotus.
Frogbit
Salvinia natans
Water hyacinth3) Bog Plants
- Bengal Canna
Aquatic plants that grow at the sides and on the banks of freshwater areas are sometimes called bog plants. These range from the grasses that grow in marshlands to Elephant Ears and Rushes. Some examples of bog plants are Arrowheads, Cattails and Reeds, Floating Hearts, Bog Irises, Louisiana Irises, Rushes, Cannas, Palms, Papyrus, Elephant Ear and Bog Taro.
Moccasin flower orchid
Acorus americanus
Sarracenia
