Water potential gradients drive the movement of water in the soil-plant-atmosphere continuum. This movement can also be characterized by the relationships between soil water (the supplier), plant sap flow via their stem and leaves (the distributor), and plant or atmospheric demand via evapotranspiration (the consumer). Currently, there is a strong understanding of the supplier and the consumer, but what about the distributor? Within the past few decades, instrumentation has been advancing to measure the water in the soil or sap flow in woody stems, but recently, there has been a resurgence in interest in measuring herbaceous stem flow. Therefore, our group has been investigating sap velocity (m s-1 ) and flow (m3 s-1 ) of corn (maize) plants in an Iowa agricultural research field using heat ratio sap flow sensors. These sensors are optimal for agricultural settings but require ancillary inputs – thermal diffusivity and the stem’s cross-sectional area – which are usually approximated as a constant throughout the plant’s life cycle. We continuously estimate thermal diffusivity under zero flow conditions throughout the season using the T-max method and measure stem diameter to estimate the cross-sectional area. Additionally, we measure sap flow at multiple heights for each plant we investigate. The aim is to develop a mass (water) balance of the plant and break up the canopy into four layers: bottom, mid bottom, mid-top, and top. We hypothesize that our methods can "see" the inverse relationship between sap velocity and sap flow between the different layers; the bottom layer has a high sap flow but a low sap velocity, and the top layer has a low sap flow but a high sap velocity, see attached figure for an example of sap velocity at 4 relative heights of a corn plant in July. Our group is motivated to better understand the movement and storage of water in crops, especially for different layers throughout the canopy, to better support remote sensing platforms that are sensitive to water. We also expect these results to contribute to a better understanding of how water moves and is distributed in corn plants, the methods used to employ sap flow sensors, and provide modelers with additional biophysical parameters.