The plants, which grow on dry habitat, are called xerophyte. These plants have anatomical and physiological modifications which may assist the plant to cope with environmental water deficit, eg, Argemone, Opuntia. The special type of xerophillous plant which grow on saline soil with high concentration of salts like NaCl, MgCl2 and MgSO4 are called halophytes. These plants produces negatively geotropic root called pneumatophore. eg, Rhizophora, Sonnertia. The plants which grow on extremly wet soil where water is available to plant are called hydrophytes eg, Wolffia, Azolla, Ceratophyllum. The plants which grow best in full sun light are called heliophytes,