A horizontal glass measuring tube with a vessel for a plant shoot at one end and having a vertical limb with a stopcock and a funnel fitted by a ground glass joint. Mounted on a wooden stand. A plant shoot is sealed into a stopper which fits the end tube, and the whole apparatus is filled with water, the open end of the capillary tube, which is graduated in millimeters, dipping into a beaker of water. For Demonstration, of transpiration rates and rates of water absorption by a cut shoot under various external conditions. The position of the air bubble may easily be adjusted by opening the glass stopcock to admit water from the central reservoir. The whole apparatus is mounted on a varnished wooden base by spring clips.