Fig. 3

Diurnal relationship between xylem flux density (J, g cm⁻² h⁻¹) and vapour pressure deficit (kPa) or solar radiation (W m⁻²) for two representative species with different mean xylem flux density. Bars indicate the standard deviation. Arrows give the direction of the diurnal course from morning to afternoon. In the right panels: D (solid line), R (grey bars), and mean J ± SE (black points with bars). Note the different scaling for J between the upper four and the lower three species. This also applies to the right panels