Figure 2.

Differences in chlorophyll distribution for three representative species. Q. alba (A–C), P. bifurcatum (D–F), and E. crassipes (G–I). At left, a typical grayscale fluorescence image is shown for each species (A, D, and G), where the yellow transect indicates the section of tissue in a single measurement; chlorenchyma domains such as palisade (PM) and spongy mesophyll (SM) are included in the measurements, whereas nonphotosynthetic structures such as veins (V), upper epidermal (UE) and lower epidermal (LE) layers, and hypodermal layers (HL) are excluded. Intercellular airspaces (IA) in E. crassipes are included in the measurements and increase local variability in mean profiles. Heat maps (B, E, and H) of the same images help to highlight trends in chlorophyll distribution. Multiple (n > 6) line profiles are measured (gray points; C, F, and I) to describe the mean chlorophyll profile (black points; C, F, and I) for an individual species. Chlorophyll content (as a percentage of the absolute chlorophyll maximum) is displayed as a function of relative depth (percentage depth from upper to lower edge of mesophyll).