On the supposed changes in stomatal frequency and size with height of leaf insertion

The hypotheses put forward by Meidner and Mansfield (1968. Physiology of stomata. London: McGraw Hill), that stomatal frequency (stomata per unit area) increases with height of insertion of leaves while stomatal size decreases, are examined using material of european trees cultivated in Canberra, Australia. The data obtained do not support the hypotheses. Measurements were also made on species of Eucalyptus native to the Canberra area or cultivated there, but again no support was offered to the hypotheses. Neither stomatal size nor frequency changed appreciably and size may even increase with height of leaf insertion. Some evidence was obtained in one species of a possible increase in size with position along the annual shoot, but this would require further work to be fully established. (C) 2000 Annals of Botany Company.