For investigating transpiration. Measures the uptake of water by a cut plant shoot. The cut shoot may be replaced by a porous pot filled with water which enables measurement of the rate of evaporation from a moist surface, thus giving indication of relative humidity. Comprises a capillary tube with mm scale connected to a syringe and an outlet via a three-way stopcock. The syringe enables adjustment of air bubble during set-up, the outlet is connected to the cut shoot or porous pot, mounted on strong vertical plate.