Leaves of plants are green in colour due to the presence of pigment chlorophyll. This pigment is responsible for carrying out photosynthesis in plants. In some plants, leaves are orange or yellow in colour it doesn't mean that they do not contain chlorophyll. It shows that such leaves contain other pigments in higher amount than chlorophyll. But such plants are capable of carrying out photosynthesis.
But there are other plants that are non green and do not contain chlorophyll. Such plants follow parasitic mode of nutrition.