Transpiration streams are induced by evaporative demand from the environment and distribute water solution from roots to tissues and cells in the respective organs through the complicated pathways. In these processes, physiological functions of plants such as stomatal movement, photosynthesis, phloem and xylem transport, nutrient uptake and expansive growth are affected by transpiration streams. Therefore, many kinds of techniques for measuring evaporative demand and transpiration streams in leaf boundary layer, leaves, fruits, stem, roots and plant canopy have been developed. The information about transpiration streams provided by the developed techniques must be more informative with cooperative measurements of plant physiological functions and must be more effective for the speaking plant approach to the environment control.