... per leaf. Stomatawere counted and stomatal density (adaxial stomatal density, SDd, and abaxial stomatal density, SDb) was calculated as the number of stomata per unit leaf area (mm−2) (Tab. ... bilateral palisade parenchyma layers [15, 24, 57, 65, 70].Leaves of P. trichocarpa are known to have a small number of large stomata and a low ratio of adaxial/abaxial stomatal den-sities [15, 22, ... canopy position, anatomical and morphological leaf characteristics (i.e. thickness of epidermis, of palisade and spongy parenchyma layers, density and length of stomata, leaf area, specific leaf...