ABSTRACT
A universally accepted definition of aquatic vascular macrophytes or hydrophytes is difficult because of the diversity of organisms and habitats associated with these plants. Hydrophytes can be considered plants that germinate in water or in saturated sediment and must spend at least a part of their cycle in water (Reid, 1961, as described by Sculthorpe, 1967). Hydrophytes belong to three classes (Kadlec and Knight, 1996): ferns (Tracheophyta), conifers (Gymnospermae), and flowering plants (Angiospermae). These last include monocots (Monocotyledonae) and dicots (Dicotyledonae). Hydrophytes may be classified according to their position in the water body as (1) emergent (example: rice, Oryza sativa L.), in which most of the plant shoot extends above the water line; (2) submergent (example: eelgrass, Zostera marina), in which stems and leaves are mostly confined between the aqueous sediment and the water surface; and (3) floating (example: water hyacinth, Eichhornia crassipes), in which fronds, leaves and stems are buoyant enough to float on the water surface. They can be anchored or free floating (Kadlec and Knight, 1996). Plant species in each of these categories may be further classified as woody, herbaceous, annual, and perennial. Submerged plants would be expected in deeper water, floating plants closer to shore, and emerged plants in shallower water and wet soil on or near the shoreline. However, communities often intermingle because of subtle changes in sediment deposits and thus, depth of rooting.
