Rate of uptake of glycine, ammonium and nitrate by intact roots of mature trees of messmate (E. obliqua), candlebark (E. rubida) and narrow-leaf peppermint (E. radiata). The rate of uptake was determined by incubating intact attached roots in equimolar (100 μmol L−1) solutions of nitrate, ammonium and glycine. Three replicate measurements were made on each of the three species at each of three sites on four occasions. There was no difference in uptake rate among sites or dates (P > 0.05) and thus these data are combined. Data are the mean of 36 replicates per species, and errors bars are standard error. Uptake rates differed significantly among forms of N (P < 0.0001), but species did not vary in their preference for different forms of N (species*N-form interaction, P > 0.05).