Figure 1.

Spatial distribution of evaporation (A and D), ψ (MPa; B and E), and T (°C; C and F) across outside-xylem leaf tissues for B. galpinii (A–C) and H. arbutifolia (D–F). In A and D, the contours represent evaporation rate from each node in the grid (which represents a finite volume of tissue within the areole) as a percentage of the transpiration rate of the leaf area subtended by that node; dashed lines indicate net evaporation of zero. The diagram at top left shows the approximate location of each tissue type. Transdermal micrographs are shown with scale bars for each species to illustrate the large differences in leaf anatomy and dimensions between the two species. Dashed white lines in A and D indicate the boundary between regions with net evaporation and regions with net condensation. Tissue-specific percentage contributions to total evaporation rate were as follows (in the order lower epidermis, spongy mesophyll, palisade mesophyll, BS, and upper epidermis): for B. galpinii, 88.4, 6.4, 2.4, 3.4, and −0.9; for H. arbutifolia, 36.6, 26.5, 9.9, 32.3, and −6.7.