The leaf surfaces of Dianthus caryophyllus plants cultured in vitro in either airtight or ventilated vessels were examined using scanning electron microscopy (SEM). The resultant hyperhydrated, non-hyperhydrated and acclimatized plants were compared for stomatal density, cuticular wax development and stomatal function. The leaf surfaces of in vitro cultured plants were basically the same as those of acclimatized plants but less wax deposition was observed on their leaves. Stomata were found both open or closed after transfer of plants ex vitro. However, stomata of in vitro leaves grown in ventilated culture vessels were more functional than plants grown in other conditions. Acclimatized plants had a normal leaf epidermal surface, and were wholly covered with waxes; their stomatal density being similar to that of highly ventilated plants but lower than that of less ventilated plants. Leaves of plants grown in airtight culture vessels or under a low number of air exchanges per hour had less waxes than plants grown at a higher number of air exchanges per hour or than acclimatized plants. In contrast, hyperhydrated plants had abnormal, malformed stomata and no wax deposition was detected. The adaxial surface of non-hyperhydrated leaves seemed more normal than the abaxial, especially in the most ventilated vessels, and this may be due to the former receiving more light and so developing in a more favourable microenvironment.