ABSTRACTThe loss of water from small bulk samples of five grass species was studied under constant conditions of humidity, temperature and lighting. A logarithmic curve was fitted to the data and the different species compared on the basis of a loss coefficient derived from the fitted curve. The species varied significantly in this aspect; those with high surface‐area to dry‐weight ratios generally lost water fastest The presence of stem material appeared to increase the rate of water loss considerably. High humidity during drying caused the grasses to lose water more slowly and to retain much more water at equilibrium with the surrounding air. Chemical treatments to speed water loss, using a solvent and a fungal toxin were tested. Both appear to have some promise. Selection for high water loss in grass breeding may also be possi