The extraction of wetland hydrophytes types based on medium resolution TM data Comparative study on the ability which utilized hydrophytes purify polluted water of river Formation of iron plaque on root surface and its effect on plant nutrition and ecological environment Effects of Weight and Store Temperature on Turion Germination and Seedling growth of Potamogeton crispus L. Cleansing of Benzene by Three Hydrophytes and Condition Optimization Effect of Morphology and Physiology of Wetland Plants on Plateaus at Different Altitudes