Aquatic Plant plants living or growing in water and often forming distinct aquatic communities. Aquatic plants are rich source of nutrients and energy and are considered to be the most efficient converters of solar energy. The importance of aquatic flora in agriculture, pisciculture and aquaculture has recently been emphasized.
In Bangladesh about 130 angiospermic, 6 pteridophytic, 3 bryophytic and several hundred algae species have been identified as aquatic plants. Some amphibious plants are also available. True aquatic plants are identified as submerged, surface immersed, dispersed and floating weeds. Other than algae about 35 species are submerged, 20 are surface immersed, and 17 are free floating.
Many aquatic plants are strictly seasonal; they start growing at the beginning of the monsoon and in July and August flourish in almost all the inundated parts of Bangladesh. The most common submerged plants are Ceratophyllum, Aponogeton, Miriophyllum, Utricularia, Blyxa, Hydrilla, Nechamendra, Ottelia, Vallisneria, Najas, Potamogeton, Ruppia and Zennichellia. The common attached floating plants are Nymphaea, Alternanthera, Ipomoea, Nymphoides, Ludwigia, Trapa, Nelumbo and Marsilea. The most common floating plants are Eichornia, Wolffia, Lemna, Spirodella, Pistia, Salvinia, Azolla and Ceratopteris. Members of sedges and grasses, Polygonum, Alisma, Pontederia, aroids and a few ferns form the dominant vegetation of shallow water bodies.
Many aquatic plants are important to the life of the inhabitants of the area. Some are used as vegetable (Alternanthera, Enhydra, Ipomoea, Nymphaea and Trapa), fodder (Hydrilla, Pistia, Coix, Hygroryza, Leersia, Panicum, Paspelidium, Lemna, Wolffia and Spirodella), medicinal plants (Nymphoides, Cyperus), and mat and basket making materials (Cyperus species, Eliocharis species). Some are used as manure. By the end of the monsoon most of the aquatic plants complete their life cycle, die, decay or dry up. They contribute significantly by adding organic matters and nutrients to the soil. Some aquatic plants are efficient in absorbing nutrients from water and have a beneficial role in reducing pollution. The common pollution abatement aquatic plants are water hyacinth, common reed, duckweed, Elodia, Hydrilla, Scirpus, Myriophyllum, Azolla and Mersilea. [Mostafa Kamal Pasha]