Plants of genus Ammannia are aquatic weeds that grow in wet places, ponds and rice fields in Egypt, Tropical Africa, West Asia to India, China, Australia, West India, North, Central and South America. The phytochemical study of Ammannia revealed the presence of new valuable secondary metabolites. In addition, this work includes the comparative study of three species of Ammannia and also supplied with morphological and microscopical studies to facilitate the identification of the plant in both the entire and powdered-forms.