Producing electricity from tree's or plant's leaf is possible. A Leaf contains approximately more than trillions of cells. During the process of photosynthesis, each cell of the leaf will emit electrons. By the movement of this trillions of electrons we can produce electricity. In another method, we can get current from leafs by means of flow of electron between two types of different plants using different metal conductors . Please refer the above figure
If we produce electricity from plant/ tree, everyone wants to be planting a tree in his / her garden. Government also motivate this process. So, the number of trees in the globe also increases. There by we can save our world from global warming.
If we produce electricity from Plants / trees, in future there is no need to worry about non-renewable energy such as petroleum. This will make pollution free green globe.
Everything Is Possible!