Assam - Ministry of Environment and Forests

A large diversity of aquatic plants belonging to angiosperms and ferns are found in the wetlands of Assam.The floating and emergent hydrophytes are well captured in the LISS III data (Plate-3), while, the submergedones are not. Some of the dominant and major hydrophytes belonging to the floating and emergent typeobserved in the state are listed here.Free Floating Hydrophytes:The species are found coming in contact with water and air only. These species has a tendency to formcomplete carpet over water surface during certain period. Usually these plants grow well in still waters atshallow depths, sometimes in very slow flowing shallow water bodies.Angiosperms:Eichhomia crassipes (Mart.) Solms.; Lemna perpusilla Torr.; Pistia stratiotes L; Spirodela polyrrhiza(L) Schleid.,S. punctata (Meyer.) Thompson; WoljJia arrhiza (L) Hook. ex WimmAquatic ferns:Azolla pinnata RBr.; Salvinia cucullata Roxb. ex Bory; S. natans (L) All.Floating leaves anchored Hydrophytes:The plants are usually in contact with soil, water as well as air. Except the developing leaves, the maturedones remain floating. The leaves frequently form a continuous cover in such an extent that water does not getwarmed. Different kinds of fishes are found to take shelter during the hottest period of the day. Usually theseplants grow well in still waters. Commonly found plants are:Aponogeton n,atans (L) Engl. & Krause; Euryale ferox Salisb; Nelumbo nucifera Gaertn.; Nymphaeanouchali Burm. f., N. pubescens Willd., N. rubra Roxb. ex. Andrews; Nymphoides cristata (Roxb.) O.Kuntze, N. indicum (L) O. Kuntze; Potamogeton octandrous Poir.; Trapa natans L var. bispinosa(Roxb.) Makino, T. natans L var. quadrispinosa (Rqxb.) Makino.Floating shoots anchored Hydrophytes:These aquatics have contact with soil, water and air. They usually grow along the margins of shallow waterpools rooted in marsh and spread branches with their shoots floating on water. The main stem remainssubmerged wholly or partially. They often produce spongy respiratory roots at the nodes. When water levelrecede these plants become terrestrial, their stems and leaves get reduced. At the advent of rains theseplants again show normal growth and development. The species are:Hygroryza aristata Nees ex Weight & Am.; Ipomoea aquatica Forsk.; Limnophila sessiliflora (Vahl) Bl.;Ludwigia adscendens (L) Hara; Myriophyllum indicum Willd., M. tuberculatum Roxb.; Neptuniaprostrata (Lam.) Bail.; Paspalidium punctatum (Burm.) A. Camus; Polygonum glabrum Willd.;Pseudoraphis brunoniana Griff.Emergent anchored Hydrophytes:Usually these plants grow along the water's edge. The roots, lower parts of stems and sometimes the lowerleaves remain submerged. The apical parts and flowers rise above the water surface. A large number ofspecies are recorded and found in abundance. Many species of the following genus are observed:Cyperu, Eleochari, Echinochloa, Hygrophila, Polygonum, Limnophila , Ranunculus, ScirpusSwamps, Marsh vegetation:This category of plants are found to grow well all along the banks of rivers and tributaries, ponds, heels,ditches, Ox-bow lakes, in swamps and marshes (locally known as 'pitoni', 'metakani', 'hola', 'torani', 'ikorani'and 'doloni') where the soil is saturated with water at least in the early part of plant life. Most of them continueto thrive even after the substratum has considerably dried. Good number of plants have been recorded andare found well distributed in almost all parts of Assam. Amongst these sedges and grasses form the largestcomponent of vegetation. Many species of the following genus occur in abundance:Alternanthera, Amaranthus, Bacopa, Blumea, Canna, Crataev, Hedyotis, Justicia, Lindemia, LudwigiaPolygonum, Ranunculus125