Narrowly speaking, the term refers to plants that live their entire lives in water, such as water lilies. More broadly speaking, the term encompasses wetland plants such as reeds that need to live in water or marshland for only one period of their life.
狹義的水生植物一生都必須生活在水中，例如睡蓮；廣義的水生植物則包括「濕生」植物，它們的生活史中，往往只有某一時期需要生存在水中或溼地上，例如蘆葦。