The biopotentials or micro electrical potentials of the plant' tissues and their effect on plant growth have been studied by plant physiologists for some time. However, practically no research has been conducted on natural electrical potentials between soil and a growing plant, or “macropotentials” of the plants. We used LandMapper ERM-03 and our patented non-polarizing electrodes made from standard AgCl-electrodes cupped with solidified agar solution of 1% KCl. The reference electrode was always placed in the topsoil near a growing plant and the measuring electrode was firmly contacted to the surface of the tissues of the plant (flowers, stems, or leaves). Natural electrical potentials of more than 60 species of native and cultural plants of Ukraine, Russia, and Philippines have been studied in 2003-2004. The electrical potential difference between soil and a plant is always negative. This difference is highest during spring and for young plants in summer, and decreases in fall when plants in Ukraine and Russia are ready for dormancy. Tropical plants showed higher potential differences than plants of temperate climate. The potentials for all plants decreased in a row flower-leaf-stem. Electrical potential of herbaceous plants is directly related with the leaf area, the highest potentials were observed for burdock, cow-parsnip, and young banana palms. The research is underway for evaluating relationship between natural electrical potentials in plants and plant's water stress.