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The morphology and physiology of trees of Eucalyptus camaldulensis growing in the field at two monsoonal and one semi-arid location were compared. In the wet season, shoot growth at the monsoonal locations was similar and larger than that at the semi-arid location. In the dry season, new shoot growth at the more humid monsoonal location (Petford) was similar to growth in the wet season while at the less humid (Katherine) and the semi-arid (Tennant Creek) locations, shoot growth was foreshortened and the leaves had larger dry weights per unit area.

In the summer wet season, leaves on both the north and south sides of the trees were maintained at or below (by up to 5 degrees C) air temperatures throughout the day except for north facing leaves at Petford which were consistently above (by up to 3 degrees C) air temperatures. Midday gas exchange in the dry season at both monsoonal localities was restricted to trees at the water’s edge, whereas most trees, including those at drier sites, at the semi-arid location exhibited significant rates of gas exchange.

The results, which are discussed in relation to environmental variables (vapour pressure deficits, wind speeds) to which the trees are exposed, and to previous results obtained in the glasshouse, indicate that the differences in shoot growth and physiology are adaptations to the environment in which the trees have evolved.