Fig. 5.

Internal resistance to CO₂ diffusion across P. dilatatum leaves. Ambient CO₂ concentrations (C_a; A, D), intercellular CO₂ concentrations (C_i; B, E), and stomatal conductance values (C, F) were determined on the adaxial (dark bars) and abaxial (white bars) surfaces of attached P. dilatatum leaves, on plants that were maintained at optimal growth temperatures. The ambient CO₂ concentration was maintained either at 2500 μl l⁻¹ on the adaxial surface and 0 μl l⁻¹ on the abaxial surface (A–C) or 2500 μl l⁻¹ on the abaxial surface and 0 μl l⁻¹ on the adaxial surface (D–F). Light was oriented to the adaxial leaf surface. Data are the mean values±SE of four plants per treatment. The different letters represent significant differences (P<0.05) and * indicates values below the level of detection.